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Risk of colorectal cancer among immigrants to Ontario, Canada

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Background The risk of colorectal cancer (CRC) varies around the world and between females and males. We aimed to compare the risk of CRC among immigrants to Ontario, Canada, to its general population. Methods We used an exposure-control matched design. We identified persons in the Immigration, Refugees and Citizenship Canada Permanent Resident Database with first eligibility for the Ontario Health Insurance Plan between July 1, 1991 and June 30, 2008 at age 40 years or older, and matched five controls by year of birth and sex on the immigrant’s first eligibility date. We identified CRC from the Ontario Cancer Registry between the index date and December 31, 2014. All analyses were stratified by sex. We calculated crude and relative rates of CRC. We estimated risk of CRC over time by the Kaplan-Meier method and compared immigrants to controls in age and sex stratified strata using log-rank tests. We modeled the hazard of CRC using Cox proportional hazards regression, accounting for within-cluster correlation by a robust sandwich variance estimation approach, and assessed an interaction with time since eligibility. Results Among females, 1877 cases of CRC were observed among 209,843 immigrants, and 16,517 cases among 1,049,215 controls; the crude relative rate among female immigrants was 0.623. Among males, 1956 cases of CRC were observed among 191,792 immigrants and 18,329 cases among 958,960 controls; the crude relative rate among male immigrants was 0.582.. Comparing immigrants to controls in all age and sex stratified strata, the log rank test p < 0.0001 except for females aged > = 75 years at index, where p = 0.01. The age-adjusted hazard ratio (HR) for CRC among female immigrants was 0.63 (95% CI 0.59, 0.67) during the first 10 years, and 0.66 (95% CI 0.59, 0.74) thereafter. Among male immigrants the age-adjusted HR = 0.55 (95% CI 0.52, 0.59) during the first 10 years and increased to 0.63 (95% CI 0.57, 0.71) thereafter. The adjusted HR > = 1 only among immigrants born in Europe and Central Asia. Conclusions The risk of CRC among immigrants to Ontario relative to controls varies by origin and over time since immigration.
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R E S E A R C H A R T I C L E Open Access
Risk of colorectal cancer among immigrants
to Ontario, Canada
Lawrence Paszat
1*
, Rinku Sutradhar
1
, Ying Liu
1
, Nancy N. Baxter
2
, Jill Tinmouth
3
and Linda Rabeneck
4
Abstract
Background: The risk of colorectal cancer (CRC) varies around the world and between females and males. We
aimed to compare the risk of CRC among immigrants to Ontario, Canada, to its general population.
Methods: We used an exposure-control matched design. We identified persons in the Immigration, Refugees and
Citizenship Canada Permanent Resident Database with first eligibility for the Ontario Health Insurance Plan between
July 1, 1991 and June 30, 2008 at age 40 years or older, and matched five controls by year of birth and sex on the
immigrants first eligibility date. We identified CRC from the Ontario Cancer Registry between the index date and
December 31, 2014. All analyses were stratified by sex. We calculated crude and relative rates of CRC. We estimated
risk of CRC over time by the Kaplan-Meier method and compared immigrants to controls in age and sex stratified
strata using log-rank tests. We modeled the hazard of CRC using Cox proportional hazards regression, accounting
for within-cluster correlation by a robust sandwich variance estimation approach, and assessed an interaction with
time since eligibility.
Results: Among females, 1877 cases of CRC were observed among 209,843 immigrants, and 16,517 cases among
1,049,215 controls; the crude relative rate among female immigrants was 0.623. Among males, 1956 cases of CRC
were observed among 191,792 immigrants and 18,329 cases among 958,960 controls; the crude relative rate
among male immigrants was 0.582.. Comparing immigrants to controls in all age and sex stratified strata, the log
rank test p< 0.0001 except for females aged > = 75 years at index, where p= 0.01. The age-adjusted hazard ratio
(HR) for CRC among female immigrants was 0.63 (95% CI 0.59, 0.67) during the first 10 years, and 0.66 (95% CI 0.59,
0.74) thereafter. Among male immigrants the age-adjusted HR = 0.55 (95% CI 0.52, 0.59) during the first 10 years
and increased to 0.63 (95% CI 0.57, 0.71) thereafter. The adjusted HR > = 1 only among immigrants born in Europe
and Central Asia.
Conclusions: The risk of CRC among immigrants to Ontario relative to controls varies by origin and over time since
immigration.
Keywords: Colorectal cancer, Cancer registry, Immigrants, Exposure-control matched design, Cox proprotional
hazards regression
Background
The incidence of CRC varies between males and females,
among individual nations and regions of the world, and
is associated with environmental, behavioural and gen-
etic factors [13]. Among nations with previously lower
incidence and current adoption of Western lifestyles, the
incidence is increasing [47], although India is a notable
example of an exception to this trend [8]. This trend has
also been described among immigrants to California
from previously lower incidence nations [9].
The incidence of CRC has been high in Canada com-
pared to most other countries. Crude and world age
standardized CRC incidence for Canada in 2012 are 68.5
and 35.2 per 100,000 respectively, compared to 50.7 and
27.0 per 100,000 respectively for Poland, 18.6 and 14.2
per 100,000 respectively for China, and 5.1 and 6.1 per
100,000 for India [10]. Lower risk of CRC among immi-
grants compared to non-immigrant populations with
* Correspondence: lawrence.paszat@ices.on.ca
1
University of Toronto, Institute for Clinical Evaluative Sciences, G106 2075
Bayview Avenue, Toronto, ON M4N3M5, Canada
Full list of author information is available at the end of the article
© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Paszat et al. BMC Gastroenterology (2017) 17:85
DOI 10.1186/s12876-017-0642-5
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
Table 1 Description of immigrants and controls
Females Immigrants Controls
Overall count
Overall count 209,843 1,049,215
Year of index date
1991 - 1995 59,210 (28.2%) 290,050 (28.2%)
1996 - 2000 53,063 (25.3%) 265,315 (25.3%)
2001 - 2005 64,922 (30.9%) 324,610 (30.9%)
2006 - 2008 32,648 (15.6%) 163,240 (15.6%)
Person years by year of index date
1991 - 1995 940,939 person-years 5,292,802 person-years
1996 - 2000 725,818 person-years 3,915,579 person-years
2001 - 2005 646,525 person-years 3496,374 person-years
2006 - 2008 225,685 person-years 1,213,181 person-years
Followup time by year of index date
1991 - 1995
Mean (SD) 15.89 years (7.59) 17.88 years (6.03)
Median (IQR) 19.76 years (9.88 - 21.55) 20.28 years (16.26 - 21.78)
1996 - 2000
Mean (SD) 13.68 years (5.18) 14.76 years (4.12)
Median (IQR) 15.40 years (13.08 - 17.27) 15.76 years (14.31 - 17.44)
2001 - 2005
Mean (SD) 9.96 years (3.48) 10.77 years (2.62)
Median (IQR) 10.84 (9.24 - 12.43) 11.19 years (9.78 - 12.56)
2006 - 2008
Mean (SD) 6.91 years (2.09) 7.43 years (1.45)
Median (IQR) 7.44 years (6.71 - 8.27) 7.64 years (7.02 - 8.35)
Age at index date
40 - 49 years 97,829 (46.6%) 489,110 (46.6%)
50 - 59 years 51,806 (24.7%) 259,489 (24.7%)
60 - 69 years 41,029 (19.6%) 204,985 (19.5%)
70 - 74 years 10,342 (4.9%) 51,447 (4.9%)
> = 75 years 8837 (4.2%) 44,184 (4.2%)
Person years by age at index date
40 - 49 years 1,235,292 person-years 6,646,937 person-years
50 - 59 years 664,305 person-years 3,624,482 person-years
60 - 69 years 470,317 person-years 2,700,938 person-years
70 - 74 years 100,008 person-years 578,455 person-years
> = 75 years 69,043.82 person-years 367,123.65 person-years
Followup time by age at index date
40 - 49 years
Mean (SD) 12.63 years (5.78) 13.59 years (5.25)
Median (IQR) 12.34 years (8.44 - 17.27) 13.17 years (9.37 - 17.83)
50 - 59 years
Mean (SD) 12.82 years (6.24) 13.97 years (5.56)
Median (IQR) 12.63 years (8.25 - 18.24) 13.56 years (9.39 - 18.82)
Table 1 Description of immigrants and controls (Continued)
60 - 69 years
Mean (SD) 11.46 years (6.46) 13.18 years (5.70)
Median (IQR) 11.42 years (6.87 - 16.66) 12.90 years (8.72 - 17.86)
70 - 74 years
Mean (SD) 9.67 years (6.16) 11.24 years (5.53)
Median (IQR) 9.32 years (4.57 - 14.15) 10.98 years (7.30 - 15.17)
> = 75 years
Mean (SD) 7.81 years (5.28) 8.31 years (5.04)
Median (IQR) 7.34 years (3.39 - 11.48) 7.89 years (4.30 - 11.70)
Males Immigrants Controls
Overall count 191,792 958,960
Year of index date
1991 - 1995 48,793 (25.4%) 243,965 (25.4%)
1996 - 2000 51,328 (26.8%) 256,640 (26.8%)
2001 - 2005 62,371 (32.5%) 311,855 (32.5%)
2006 - 2008 29,300 (15.3%) 146,500 (15.3%)
Person years by year of index date
1991 - 1995 744,331 person-years 4,121,283 person-years
1996 - 2000 685,887 person-years 3,702,915 person-years
2001 - 2005 601,385 person-years 3,273,836 person-years
2006 - 2008 196,843 person-years 1,062,171 person-years
Followup time by year of index date
1991 - 1995
Mean (SD) 15.25 years (7.73) 16.89 (6.58)
Median (IQR) 19.45 years (8.28 - 21.30) 19.78 (13.12 - 21.56)
1996 - 2000
Mean (SD) 13.36 years (5.32) 14.43 (4.34)
Median (IQR) 15.22 years (11.58 - 17.15) 15.56 (14.16 - 17.32)
2001 - 2005
Mean (SD) 9.64 years (3.69) 10.50 (2.88)
Median (IQR) 10.62 years (9.03 - 12.36) 11.04 (9.50 - 12.50)
2006 - 2008
Mean (SD) 6.72 years (2.26) 7.25 (1.66)
Median (IQR) 7.37 years (6.58 - 8.24) 7.56 (6.90 - 8.31)
Age at index date
40 - 49 years 106,112 (55.3%) 530,757 (55.3%)
50 - 59 years 40,062 (20.9%) 200,563 (20.9%)
60 - 69 years 31,575 (16.5%) 157,362 (16.4%)
70 - 74 years 8070 (4.2%) 40,492 (4.2%)
> = 75 years 5973 (3.1%) 29,786 (3.1%)
Person years by age at index date
40 - 49 years 1,289,734 person-years 7,047,301 person-years
50 - 59 years 485,469 person-years 2,620,618 person-years
60 - 69 years 344,004 person-years 1,886,805 person-years
70 - 74 years 69,618 person-years 390,565 person-years
Paszat et al. BMC Gastroenterology (2017) 17:85 Page 2 of 11
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high prevalence of CRC has been described in Canada
[11, 12], the USA [13], and the UK [14].
We aimed to compare the risk of CRC among immi-
grants to Ontario, Canada, to its general population, and
to examine if the risk changed over time since arrival,
stratified by world region of birth and country of birth
of immigrants. Ontario recently established a CRC
screening program, ColonCancerCheck (CCC), [15],
consisting of biennial guaiac fecal occult blood testing
(gFOBT) for persons 50 - 74 without a first degree rela-
tive affected by CRC (approximately 89% of the popula-
tion of Ontario), and screening colonoscopy for those
with an affected first degree relative (approximately 11%
of the population of Ontario) [16, 17]. CCC sends letters
to all 5074 year old residents of Ontario inviting them
to discuss CRC screening with their primary care pro-
viders, who are supplied with gFOBT sampling kits to
distribute to their eligible patients. It is already known
that immigrants to Ontario are less likely to participate
in colorectal screening than non-immigrants [18], as is
true elsewhere in North America and Europe [1922].
The goal of this work is to inform CCC of the risk of
CRC stratified by origin of immigrants and time since
immigration, so that its efforts to improve screening par-
ticipation among immigrants may be tailored by this
information.
Methods
This work was approved by the Research Ethics Board of
Sunnybrook Health Sciences Centre and conducted at
the Institute for Clinical Evaluative Sciences (ICES). We
used three population-wide databases, in which each
observation is identified by an encryption of the unique
Ontario Health Insurance Number and are thereby link-
able deterministically. The Immigration, Refugees and
Citizenship Canada Permanent Resident Database
(IRCC) contains the date of arrival in Canada, the
intended province of residence in Canada, and the coun-
try of birth; permission to access the data was granted
by the Government of Canada. The Registered Persons
Database (RPDB) contains the age, sex, dates of eligiblity
for the universal, single-payer Ontario Health Insurance
Plan (OHIP), date of last contact with health care ser-
vices in Ontario, and status on the date of last contact
for each OHIP beneficiary; permission to access the data
was granted by the Ministry of Health and Long Term
Care of Ontario. The Ontario Cancer Registry (OCR)
contains the diagnosis code for invasive cancer (Inter-
national Classification of Diseases version 10) and its
date of diagnosis, for all residents of Ontario diagnosed
with a malignancy; permission to access the data was
granted by Cancer Care Ontario.
We used an exposure-control matched design. We
identified persons from the IRCC with arrival in Ontario,
and whose first eligibility for OHIP fell between July 1,
1991 and June 30, 2008 at age 40 years or older, in the
Registered Persons Database (RPDB). The first eligibility
date was labeled the index date for each immigrant.
From the IRCC, we extracted country of birthfor each
immigrant, and categorized country of birthinto a
modified classification of selected world regions (East
Asia and Pacific; Europe and Central Asia; Latin Amer-
ica and Caribbean, Middle East and North Africa, South
Asia, Sub-saharan Africa) [2325]. We matched 5 con-
trols from the RPDB alive on the corresponding immi-
grants index date and not found in the IRCC database
between 1986 to 2010, on year of birth and sex.
We identified CRC (diagnosis codes C180, C182 -
C189, C19, C20) from the OCR among immigrants and
controls between the index date and December 31, 2014.
All immigrants and controls were followed to date of
last contact, date of CRC diagnosis, or December 31,
2014, whichever came first.
We examined the distributions of various characteris-
tics between immigrants and controls in the matched
cohort. All analyses were stratified by sex. The crude
rates of CRC (per 100,000 person-years) among immi-
grants and controls, along with the corresponding crude
relative rate of CRC, were calculated.
To examine the association between immigration
status and the hazard of CRC, the outcome was de-
fined as the time to diagnosis of CRC (from the index
date). Individuals were censored at the time of study
end or death, whichever occurred first. Kaplan Meier
methods were used to graphically examine the risk of
CRC over time among immigrants compared to
Table 1 Description of immigrants and controls (Continued)
> = 75 years 39,621 person-years 214,918 person-years
Followup time by age at index date
40 - 49 years
Mean (SD) 12.15 years (5.85) 13.28 years (5.23)
Median (IQR) 12.12 years (8.09 - 16.70) 13.09 years (9.31 - 17.36)
50 - 59 years
Mean (SD) 12.12 years (6.11) 13.07 years (5.57)
Median (IQR) 11.90 years (7.75 - 17.18) 12.61 years (8.69 - 17.70)
60 - 69 years
Mean (SD) 10.89 years (6.39) 11.99 years (5.77)
Median (IQR) 10.81 years (6.36 - 15.76) 11.65 years (7.81 - 16.43)
70 - 74 years
Mean (SD) 8.63 years (5.80) 9.65 years (5.29)
Median (IQR) 8.16 years (3.81 - 12.62) 9.11 years (6.09 - 13.08)
> = 75 years
Mean (SD) 6.63 years (5.03) 7.22 years (4.66)
Median (IQR) 6.18 years (2.18 - 9.90) 6.90 years (3.39 - 10.31)
Paszat et al. BMC Gastroenterology (2017) 17:85 Page 3 of 11
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Table 2 Crude rates of CRC among immigrants and controls and crude relative rate among immigrants
Females Immigrants CRC among
immigrants
Controls CRC among
controls
Crude rate among
immigrants
a
Crude rate
among
controls
a
Crude relative
rate among
immigrants
a
Overall 209,843 1877 1,049,215 16,517 0.203 0.325 0.623
Age at index date
40 - 49 years 97,829 (46.6%) 442 (23.5%) 489,110 (46.6%) 3180 (19.3%) 0.098 0.131 0.748
50 - 59 years 51,806 (24.7%) 428 (22.8%) 259,489 (24.7%) 4299 (26.0%) 0.177 0.325 0.543
60 - 69 years 41,029 (19.6%) 606 (32.3%) 204,985 (19.5%) 6027 (36.5%) 0.353 0.611 0.577
70 - 74 years 10,342 (4.9%) 200 (10.7%) 51,447 (4.9%) 1720 (10.4%) 0.548 0.815 0.673
> = 75 years 8837 (4.2%) 201 (10.7%) 44,184 (4.2%) 1291 (7.8%) 0.798 0.963 0.828
Selected world regions
of birth
205,469 1854 1,027,345 16,217
East Asia and Pacific 67,385 (32.8%) 748 (40.4%) 336,925 (32.8%) 5771 (35.6%) 0.253 0.345 0.731
Europe and Central
Asia
38,315 (18.7%) 599 (32.3%) 191,575 (18.7%) 3107 (19.2%) 0.340 0.331 1.027
Latin America and
the Caribbean
23,210 (11.3%) 191 (10.3%) 116,050 (11.3%) 1789 (11.0%) 0.176 0.310 0.569
Middle East and
North Africa
16,222 (7.9%) 106 (5.7%) 81,110 (7.9%) 1114 (6.9%) 0.155 0.298 0.519
South Asia 52,103 (25.4%) 162 (8.7%) 260,515 (25.4%) 3764 (23.2%) 0.072 0.308 0.233
Sub-saharan Africa 8234 (4.0%) 48 (0.3%) 41,170 (4.0%) 672 (4.1%) 0.134 0.344 0.389
Selected nations of
birth
146,545 1230 732,725 11,565
India 29,744 (20.3%) 73 (5.9%) 148,720 (20.3%) 2173 (18.8%) 0.059 0.315 0.187
Pakistan 7907 (5.4%) 18 (1.5%) 39,535 (5.4%) 435 (3.8%) 0.056 0.247 0.226
Sri Lanka 10,256 (7.0%) 48 (3.9%) 51,280 (7.0%) 893 (7.7%) 0.093 0.343 0.270
China / Hong Kong /
Taiwan
39,886 (27.2%) 535 (43.5%) 199,430 (27.2%) 3679 (31.8%) 0.308 0.364 0.845
Philippines 16,461 (11.2%) 125 (7.6%) 82,305 (11.2%) 1232 (10.7%) 0.171 0.316 0.542
Korea 4194 (2.9%) 25 (2.0%) 20,970 (2.9%) 239 (2.1%) 0.145 0.249 0.585
Iran 6754 (4.6%) 40 (3.3%) 33,770 (4.6%) 443 (3.8%) 0.139 0.287 0.484
Poland 5373 (3.7%) 83 (6.8%) 26,865 (3.7%) 544 (4.7%) 0.287 0.351 0.818
Guyana 5072 (3.5%) 30 (2.4%) 25,360 (3.5%) 447 (3.9%) 0.116 0.333 0.349
Jamaica 5012 (3.4%) 65 (5.3%) 25,060 (3.4%) 427 (3.7%) 0.260 0.332 0.783
United States of
America
3906 (2.7%) 18 (1.5%) 19,530 (2.7%) 258 (2.2%) 0.127 0.279 0.454
Russia 4686 (3.2%) 70 (5.7%) 23,430 (3.2%) 288 (2.5%) 0.352 0.283 1.244
United Kingdom 3734 (2.6%) 43 (3.5%) 18,670 (2.6%) 299 (2.6%) 0.292 0.356 0.819
Ukraine 3560 (2.4%) 57 (4.6%) 17,800 (2.4%) 208 (1.8%) 0.367 0.264 1.389
Males
Overall 191,792 1956 958,960 18,329 0.240 0.413 0.582
Age at index date
40 - 49 years 106,112 (55.3%) 580 (29.7%) 530,757 (55.3%) 4758 (26.0%) 0.123 0.185 0.666
50 - 59 years 40,062 (20.9%) 476 (24.3%) 200,563 (20.9%) 4671 (25.5%) 0.269 0.488 0.550
60 - 69 years 31,575 (16.5%) 610 (31.2%) 157,362 (16.4%) 6237 (34.0%) 0.486 0.906 0.536
70 - 74 years 8070 (4.2%) 168 (8.6%) 40,492 (4.2%) 1676 (9.1%) 0.661 1.176 0.562
> = 75 years 5973 (3.1%) 122 (6.2%) 29,786 (3.1%) 987 (5.4%) 0.844 1.258 0.670
Selected world regions
of birth
187,835 1923 939,175 17,999
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controls, and log-log plots were used to assess if the
hazard functions were proportional. Multivariable
extended Cox regression models were then imple-
mented, controlling for baseline characteristics [26].
Note that since we performed exposure-control
matching, as opposed to case-control matching, the
matched characteristics are permitted in the multivar-
iable model. To account for within-cluster correlation
that may arise due to the matched design, a robust sand-
wich variance estimation approach was used. As it was
possible for the association between immigration status
and hazard of CRC to change over time, we included an
interaction between immigration status (immigrant or
non-immigrant) and time, where time was categorized
into two intervals using the point of 10 years after index
[27]. Analyses were conducted with SAS version 9.3 (SAS
Institute, Inc., Cary, NC). All statistical tests were two
sided, and Pvalues less than .05 were considered statisti-
cally significant.
Results
We identified 209,843 female immigrants with 2,538,966
person-years of follow-up to death, diagnosis of CRC, or
December 31, 2014, whichever came first. The index
date for 84.4% of female immigrants fell between July 1,
1991 and December 31, 2005 (i.e. between 9 and 23 years
prior to the last available date for records of CRC diag-
nosis). We matched them to 1,049,215 controls with
13,917,936 person-years of follow-up. We identified
191,792 male immigrants (for whom the index date fell
between July 1, 1991 and December 31, 2005 among
84.7%) with 2,228,448 person-years of follow-up and
matched them to 958,960 controls with 12,160,208
person-years of follow-up (Table 1). Mean and median
duration follow-up of followup are modestly longer for
controls compared to immigrants; this is due to higher
emigration from Ontario among immigrants compared
to controls, rather than higher mortality. The crude rela-
tive death rate among immigrants compared to controls
is 0.555 per 100,000 person-years, and is lower among
all strata of age at index and among all world regions
and countries of birth of immigrants (data not shown).
Among female immigrants, 58.2% had been born in the
East Asia and Pacific or the South Asia world regions, and
146,545 / 209,843 (69.8%) had been born in one of 14
among all 211 represented countries of birth, with 27.2%
Table 2 Crude rates of CRC among immigrants and controls and crude relative rate among immigrants (Continued)
East Asia and Pacific 56,546 (30.1%) 787 (40.9%) 282,730 (30.1%) 6209 (34.5%) 0.330 0.464 0.711
Europe and Central
Asia
32,489 (17.3%) 570 (29.6%) 162,445 (17.3%) 2968 (16.5%) 0.386 0.377 1.024
Latin America and
the Caribbean
17,474 (9.3%) 136 (7.1%) 87,370 (9.3%) 1591 (8.8%) 0.174 0.385 0.452
Middle East and
North Africa
18,355 (9.8%) 164 (8.5%) 91,775 (9.8%) 1589 (8.8%) 0.221 0.389 0.570
South Asia 54,756 (29.2%) 205 (10.7%) 273,780 (29.2%) 5025 (27.9%) 0.090 0.413 0.218
Sub-saharan Africa 8215 (4.4%) 61 (3.2%) 41,075 (4.4%) 617 (3.4%) 0.180 0.329 0.545
Selected nations of birth 133,234 1341 666,170 13,209
India 30,557 (22.9%) 98 (7.3%) 152,785 (22.9%) 3028 (22.9%) 0.079 0.450 0.177
Pakistan 10,875 (8.2%) 34 (2.5%) 54,375 (8.2%) 697 (5.3%) 0.078 0.291 0.268
Sri Lanka 8005 (6.0%) 58 (4.3%) 40,025 (6.0%) 930 (7.0%) 0.150 0.489 0.307
China / Hong Kong / Taiwan 35,957 (27.0%) 562 (41.9%) 179,785 (27.0%) 4246 (32.1%) 0.376 0.495 0.759
Philippines 11,588 (8.7%) 115 (8.6%) 57,940 (8.7%) 1152 (8.7%) 0.229 0.433 0.528
Korea 4257 (3.2%) 41 (3.1%) 21,285 (3.2%) 252 (1.9%) 0.234 0.255 0.920
Iran 7381 (5.5%) 86 (6.4%) 36,905 (5.5%) 636 (4.8%) 0.279 0.385 0.724
Poland 3343 (2.5%) 70 (5.2%) 16,715 (2.5%) 373 (2.8%) 0.383 0.377 1.017
Guyana 3601 (2.7%) 31 (2.3%) 18,005 (2.7%) 427 (3.2%) 0.176 0.471 0.374
Jamaica 3496 (2.6%) 31 (2.3%) 17,480 (2.6%) 335 (2.5%) 0.184 0.394 0.466
United States of
America
3506 (2.6%) 28 (2.1%) 17,530 (2.6%) 289 (2.2%) 0.230 0.372 0.618
Russia 3662 (2.8%) 71 (5.3%) 18,310 (2.8%) 256 (1.9%) 0.463 0.316 1.464
United Kingdom 4142 (3.1%) 62 (4.6%) 20,710 (3.1%) 370 (2.8%) 0.373 0.405 0.921
Ukraine 2864 (2.1%) 54 (4.0%) 14,320 (2.1%) 218 (1.7%) 0.437 0.344 1.269
a
per 100,000 person-years
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Content courtesy of Springer Nature, terms of use apply. Rights reserved.
having been born in China / Hong Kong / Taiwan and
20.3% in India. Among male immigrants, 59.3% had been
born in the East Asia and Pacific or South Asia world re-
gions, and133,234 / 191,792 (69.5%) had been born in one
of 14 among all 213 represented countries of birth, with
27.0% having been born in China / Hong Kong / Taiwan
and 22.9% in India (Table 2). Among females, 1877 cases
of CRC were observed among immigrants and 16,517
among controls; the crude rate of CRC among female im-
migrants was 0.203 per 100,000 person-years, compared
to 0.325 per 100,000 person-years among female controls,
increased by age at index date, and varied by world region
and by country of birth Overall, the crude relative rate of
CRC among female immigrants was 0.623, ranging from
0.233 among those born in South Asia to 1.027 among
those born in Europe and Central Asia. The crude relative
rate exceeded 1.000 for those born in Russia and Ukraine.
Among males, 1956 cases of CRC were observed among
immigrants and 18,329 among controls; the crude rate
among immigrants was 0.24 per 100,000 person-
years, compared to 0.413 among controls, increased
by age at index date, and varied by world region and
country of birth. Compared to male controls, the
overall crude relative event rate among male immi-
grants was 0.582. Among world regions, the crude
relative rates of CRC for immigrants ranged from
0.218 for those born in South Asia to 1.024 for
Europe and Central Asia. The crude relative rate of
CRC exceeded 1.000 for those born in Poland,
Russia, and Ukraine (Table 2).
By the Kaplan-Meier method, the risk of colorectal
cancer diagnosis over time was consistently higher
among female controls compared to immigrants in all
age strata (log rank test p< 0.0001 except for females
Fig. 1 Forest plot for Adjusted Hazard Ratio for CRC among females by birth country
Paszat et al. BMC Gastroenterology (2017) 17:85 Page 6 of 11
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
> = 75 years of age, log rank test p= 0.01), and among
male controls compared to immigrants (log rank test
p< 0.0001 in all age strata). Examination of sex and age
stratified log-log plots of time to colorectal cancer dem-
onstrated that the hazards of CRC were proportional in
all sex and age strata. (not shown).
The age-adjusted hazard ratio (HR) for CRC among fe-
male immigrants was 0.63 (95% CI 0.59, 0.67) during the
first 10 years after arrival, and 0.66 (95% CI 0.59, 0.74)
thereafter. Among male immigrants the age-adjusted
HR = 0.55 (95% CI 0.52, 0.59) during the first 10 years,
and 0.63 (95% CI 0.57, 0.71) thereafter.
The age-adjusted HRs vary among the world regions,
and in general are significantly less than 1.00 except
among those born in Europe and Central Asia. The
point estimates of the age-adjusted HRs > 10 years after
the index date are increased compared to <= 10 years
for some regions and the respective 95% confidence in-
tervals include unity. Figures 1 and 2 display forest plots
of the stratified age-adjusted HRs for CRC for the 14
countries of birth with the largest number of immi-
grants, for females and males respectively. There are
greater differences in age-adjusted HRs among these 14
countries of birth compared to those among the seven
world regions of birth in Table 3.
Discussion
The risk of CRC among immigrants who arrived in On-
tario at the age of 40 years or older, between 1991 and
2008, is lower overall compared to age-matched controls
for more than 10 years after immigration. Their risk varies
among world regions of birth, and among the 14 countries
in which the majority of immigrants were born. All arrived
in Ontario prior to the inception of the CCC screening
Fig. 2 Forest plot for Adjusted Hazard Ratio for CRC among males by birth country
Paszat et al. BMC Gastroenterology (2017) 17:85 Page 7 of 11
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
Table 3 Adjusted cox models of CRC risk stratified by sex
Variable Females Males
Univariate HR
(95% CI)
Multivariate HR
(95% CI)
Multivariate HR
(95% CI) with
interaction
Univariate HR
(95% CI)
Multivariate HR
(95% CI)
Multivariate HR
(95% CI) with
interaction
Overall
Immigrant 0.63 (0.60, 0.66) 0.64 (0.61, 0.67) 0.59 (0.56, 0.62) 0.59 (0.56, 0.62)
Nonimmigrant controls Reference Reference Reference Reference
Age at index
40 - 49 Reference Reference Reference Reference Reference Reference
50 - 59 2.35 (2.25, 2.45) 2.35 (2.25, 2.45) 2.35 (2.25, 2.45) 2.59 (2.50, 2.70) 2.60 (2.50, 2.70) 2.60 (2.50, 2.70)
60 - 69 4.54 (4.36, 4.73) 4.53 (4.35, 4.72) 4.53 (4.35, 4.72) 4.94 (4.77, 5.12) 4.94 (4.77, 5.12) 4.94 (4.77, 5.12)
70 - 74 6.54 (6.19, 6.91) 6.52 (6.17, 6.88) 6.52 (6.17, 6.88) 6.99 (6.62, 7.37) 6.98 (6.62, 7.37) 6.98 (6.62, 7.37)
> = 75 8.63 (8.11, 9.17) 8.63 (8.12, 9,17) 8.63 (8.12, 9.17) 8.46 (7.93, 9.03) 8.47 (7.94, 9.04) 8.47 (7.94, 9.04)
Immigrant < = 10 years
since index date
0.62 (0.58, 0.66) 0.63 (0.59, 0.67) 0.55 (0.52, 0.59) 0.55 (0.52, 0.59)
Controls <= 10 years since
index date
Reference Reference Reference Reference
Immigrant > 10 years
since index date
0.65 (0.58, 0.73) 0.66 (0.59, 0.74) 0.64 (0.57, 0.72) 0.63 (0.57, 0.71)
Controls <= 10 years since
index date
Reference Reference Reference Reference
Age adjusted models for
world region of birth
East Asia and Pacific
Immigrant < = 10
years since index date
0.70 (0.63, 0.78) 0.72 (0.65, 0.80) 0.70 (0.64, 0.78) 0.72 (0.65, 0.79)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Immigrant > 10
years since index date
0.79 (0.66, 0.95) 0.80 (0.67, 0.96) 0.74 (0.62, 0.89) 0.73 (0.61, 0.87)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Europe and Central Asia
Immigrant< = 10
years since index date
1.10 (0.98, 1.23) 1.09 (0.97, 1.22) 1.02 (0.90, 1.15) 1.01 (0.90, 1.14)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Immigrant > 10 years
since index date
0.96 (0.77, 1.18) 0.96 (0.78, 1.19) 1.05 (0.85, 1.30) 1.04 (0.84, 1.29)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Latin America and the
Caribbean
Immigrant < = 10
years since index date
0.58 (0.47, 0.71) 0.59 (0.48, 0.72) 0.45 (0.35, 0.57) 0.46 (0.36, 0.58)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Immigrant > 10 years
since index date
0.56 (0.39, 0.81) 0.58 (0.41, 0.84) 0.46 (0.30, 0.71) 0.46 (0.30, 0.71)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Middle East and North
Africa
Paszat et al. BMC Gastroenterology (2017) 17:85 Page 8 of 11
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
program and many of those diagnosed with CRC received
the diagnosis prior to its inception. It is already known
that immigrants to Ontario are less likely to participate in
CRC screening [18]. In its future efforts to improve par-
ticipation in CRC screening by immigrants, CCC should
include tailored approaches to the sizable numbers of im-
migrants from countries of birth for which the age-
adjusted risks of CRC are close to, or equivalent to, those
of the non-immigrant controls.
This is an important study comprising a large popula-
tion of 401,635 immigrants from 213 countries. The
available data elements are appropriate for a time-to-
event analytic approach, that is more powerful and illu-
minating than crude rates and incidence ratios, and it
was possible to examine the potential interaction be-
tween status as an immigrant and time since immigra-
tion. Prior studies of the risk of CRC among immigrants
have substantial weaknesses compared to this work. A
national study among immigrants to Canada from 1980
to 1990, using probabilistic rather than deterministic
linkage, with followup for CRC among other cancer
types to 1998, had fewer immigrants despite being
nation-wide, 90.8% of whom were <= 44 years of age at
the time of immigration [11]. The young age distribution
is reflected in the low number of cases of CRC observed
among immigrants (n= 71 compared to n= 3833); the
low number of cases prevented the use of time to event
analytic methods and stratification by country of birth.
Other Canadian studies of small numbers of immigrants
were unable to use to time to event methods and did
not examine the worldwide distribution of origin of im-
migrants [12, 28]. Studies from the US [13] and the UK
[14] examined relative rates between immigrants from a
limited number of origins.
A limitation of the study is the inability to match im-
migrants to controls on comorbidity or past medical his-
tory on the matching date. Although immigrants and
controls hypothetically could be linked to census-level
ecologic measures of socio-economic status by postal
code on the matching date, we doubt that those mea-
sures at the time of the arrival of immigrants in Ontario
would be valid descriptors of socio-economic influences
on the health of the immigrants up to the time of their
arrival. A further limitation is the lack of data about the
risks of CRC beyond two decades since arrival, which
might plausbility increase as observed among certain
ethnic groups in California [9]. We are unable to com-
ment on the association of colorectal screening with im-
migration status, or the association between colorectal
screening among immigrants and their risk of colorectal
Table 3 Adjusted cox models of CRC risk stratified by sex (Continued)
Immigrant< = 10
years since index date
0.52 (0.40, 0.67) 0.52 (0.40, 0.68) 0.49 (0.39, 0.61) 0.48 (0.38, 0.60)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Immigrant > 10 years
since index date
0.54 (0.33, 0.87) 0.54 (0.34, 0.88) 0.72 (0.49, 1.07) 0.70 (0.47, 1.03)
Controls <= 10 years
since index date
Reference Reference Reference Reference
South Asia
Immigrant < = 10
years since index date
0.23 (0.19, 0.28) 0.24 (0.19, 0.29) 0.17 (0.14, 0.21) 0.18 (0.14, 0.22)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Immigrant > 10 years
since index date
0.24 (0.17, 0.35) 0.25 (0.17, 0.37) 0.28 (0.20, 0.40) 0.28 (0.20, 0.40)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Sub-saharan Africa
Immigrant < = 10
years since index date
0.27 (0.17, 0.43) 0.27 (0.17, 0.43) 0.39 (0.26, 0.59) 0.38 (0.25, 0.57)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Immigrant > 10 years
since index date
0.56 (0.26, 1.18) 0.56 (0.26, 1.18) 0.78 (0.40, 1.53) 0.75 (0.38, 1.48)
Controls <= 10 years
since index date
Reference Reference Reference Reference
Paszat et al. BMC Gastroenterology (2017) 17:85 Page 9 of 11
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
cancer in this study, because the population-based CRC
screening programme in Ontario was introduced near
the end of the observation period.
The variability of the risk of CRC among immigrants
to Ontario relative to controls, by region or country of
origin, has implications for colorectal screening in On-
tario. Efforts to improve screening participation among
immigrants may be tailored by this information. Further-
more, the risk of CRC should be monitored during the
period beyond two decades since arrival.
Conclusions
The risk of CRC among immigrants to Ontario varies by
length of time residing in Ontario and birthplace, and,
with the exception of those born in the Europe andCen-
tral Asia region, and in the individual countries of Russia
and Ukraine, is lower than that for non-immigrants for
up to two decades after arrival.
Abbreviations
CCC: Colon Cancer Check; CI: Confidence interval; CRC: Colorectal cancer;
HR: Hazard ratio; ICES: Institute for Clinical Evaluative Sciences;
IRCC: Immigration, Refugees and Citizenship Canada; OCR: Ontario Cancer
Registry; OHIP: Ontario Health Insurance Plan
Acknowledgements
This study is based on data and information from the Government of
Canada (Immigration, Refugees and Citizenship Canada (IRCC)'s Permanent
Resident Database), the Ministry of Health and Long Term Care of Ontario
(RPDB and OHIP), and Cancer Care Ontario (OCR). The opinions, results, view,
and conclusions reported in this paper are those of the authors and do not
necessarily reflect those of the Government of Canada, the Ministry of Health
and Long Term Care of Ontario or Cancer Care Ontario. No endorsement by
the Government of Canada, the Ministry of Health and Long Term Care of
Ontario, or Cancer Care Ontario is intended or should be inferred.
Funding
This work was funded by an Applied Cancer Research Unit grant from
Cancer Care Ontario to Lawrence Paszat. Cancer Care Ontario had no role in
the design of the study and collection, analysis, and interpretation of data
and in writing the manuscript. This study was supported by the Institute for
Clinical Evaluative Sciences (ICES), which is funded by an annual grant from
the Ontario Ministry of Health and Long-Term Care (MOHLTC).
Availability of data and materials
The data set from this study is held securely in coded form at the Institute for
Clinical Evaluative Sciences (ICES). While data sharing agreements prohibit ICES
from making the data set publicly available, access may be granted to those
who meet pre-specified criteria for confidential access (www.ices.on.ca/DAS).
The full data set creation plan is available from the authors upon request. The
data that support the findings of this study are available from the Government
of Canada (Immigration, Refugees and Citizenship Canada Permanent Resident
Database), the Ontario Ministry of Health and Long Term Care (Ontario Health
Insurance Plan and Registered Persons Database), and Cancer Care Ontario
(Ontario Cancer Registry) but restrictions apply to the availability of these data,
which were used under license for the current study, and so are not publicly
available. Data are however available from the Government of Canada, the
Ontario Ministry of Health and Long Term Care, and Cancer Care Ontario
respectively, to qualified and approved investigators.
Authorscontributions
This research was designed by LP, RS, NB, JT and LR. The data were extracted
and analyzed by YL under the supervision of LP and RS. The data were
interpreted by LP, RS, NB, JT and LR. The manuscript was drafted by LP. All
authors read and approved the final manuscript.
Ethics approval and consent to participate
This research was approved by the Research Ethics Board of Sunnybrook
Health Sciences Centre. All data had been previously stripped of personal
identifiers so that consent to participate was not required.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
PublishersNote
Springer Nature remains neutral with regard to jurisdictional claims in published
maps and institutional affiliations.
Author details
1
University of Toronto, Institute for Clinical Evaluative Sciences, G106 2075
Bayview Avenue, Toronto, ON M4N3M5, Canada.
2
University of Toronto, St
Michaels Hospital, 30 Bond Street, Toronto, ON M5B1W8, Canada.
3
University
of Toronto, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue,
Toronto, ON M4N3M5, Canada.
4
University of Toronto, Prevention and
Cancer Control, Cancer Care Ontario, 620 University Avenue, Toronto, ON
M4, Canada.
Received: 3 March 2017 Accepted: 29 June 2017
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... Importantly, CRC screening rates are not uniform across the province's ethnoculturally diverse immigrant groups, with only 31% of East Asian immigrants being overdue for CRC screening versus 44% of immigrants from Eastern Europe and from South Asia [10]. Similarly, research has found that, although immigrants overall have a lower risk of developing CRC than those who are Canadian-born, immigrants from Eastern European countries have previously been shown to have a higher risk [11]. It is possible that inequalities in CRC screening according to immigrant status may lead to inequalities in stage of diagnosis of CRC. ...
... In Canada, most immigrants must submit to a medical examination to ensure they do not burden Canada's health and social services system [28]. Canadian studies have found that morbidity and mortality due to chronic diseases are lower among immigrants than among the general population and in Ontario, immigrants have lower incidence of CRC [11,29,30]. Differences in risk factors for CRC between immigrants and long-term residents may also play a role in our findings, and these risk factors may themselves also be related to the healthy immigrant effect. ...
... In line with these international findings, we found men from European and Central Asian countries to have higher likelihood of late-stage diagnosis. Immigrants from this region have also been found to have the lowest rates of CRC screening in Ontario among immigrant groups and to be the only immigrant group with an adjusted risk of developing CRC greater than that of Canadian-born [10,11]. Our findings confirm the important role that primary care plays in early diagnosis of CRC. ...
Article
Full-text available
Background Colorectal cancer (CRC) is the second most common cause of cancer death in Canada. Immigrants in Ontario, Canada’s most populous province, are known to have lower rates of CRC screening, but differences in stage of CRC diagnosis are not known. Methods We utilized linked administrative databases to compare early (stage I–II) versus late (stage III–IV) stage of CRC diagnosis for immigrants versus long-term residents among patients diagnosed in Ontario between 2012 and 2017 ( n = 37,717) and examined the association of immigration-related, sociodemographic, and healthcare-related factors with stage. Results Almost 45% of those with CRC were diagnosed at a late stage. Immigrants were slightly more likely to be diagnosed at a late stage than their long-term resident counterparts [Adjusted relative risks (ARRs) 1.06 (95% CI 1.02–1.10)], but after adjusting for age and sex, this difference was no longer significant. In fully adjusted models, we observed a higher likelihood of late-stage diagnosis for people with the fewest co-morbidities (ARR 0.86 [95% CI 0.83–0.89]) and those with no visits to primary care (versus a high level of continuity of care) [ARR 1.07 (95% CI 1.03–1.12)]. Conclusion Immigrants were not more likely to have a late-stage CRC diagnosis after adjusting for relevant factors, but access to primary care and healthcare contact was significantly associated with diagnostic stage. Impact Attachment to a primary care provider who provides regular preventive care may play a role in more favorable stage at diagnosis for CRC and thus should be a healthcare system priority.
... Those authors indicated there was a significant deviation for morbidity over time in the healthy immigrant effect, and there were no identifiable underlying reasons for health deterioration [6]. Moreover, Paszat et al. (2017) found that immigration was a determinant for developing colorectal cancer after the first 10 years of arrival in Canada [42]. Another study reported that Canadian immigrants demonstrated lower cancer-specific mortality, but this benefit diminished over time. ...
... Those authors indicated there was a significant deviation for morbidity over time in the healthy immigrant effect, and there were no identifiable underlying reasons for health deterioration [6]. Moreover, Paszat et al. (2017) found that immigration was a determinant for developing colorectal cancer after the first 10 years of arrival in Canada [42]. Another study reported that Canadian immigrants demonstrated lower cancer-specific mortality, but this benefit diminished over time. ...
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Background: Nearly 22% of the Canadian population are first-generation immigrants. We investigated immigrants' health status and health deterioration over time in terms of the prevalence of chronic diseases (CDs) and their relationship to vitD status. Methods: We used cycles three (2012-2013) and four (2014-2015) of the Canadian Health Measures Survey. These data contained unique health information and direct physical/blood measures, including serum 25-hydroxyvitamin D (S-25(OH)D). Indicators of health status and deterioration were the prevalence of CDs diagnosed by healthcare professionals, self-reported general and mental health, and CD-related biomarkers. Results: The data (N=11,579) included immigrants from more than 153 countries. Immigrants were healthier than non-immigrants for most health status measures. The prevalence of CDs was higher among those who migrated to Canada aged ≥18 years. Longer time in Canada after immigration was associated with a higher risk for CDs. The mean S-25(OH)D was lower among immigrants, higher among patients with CDs, and inversely associated with glycated hemoglobin, total choles-terol/high-density lipoprotein ratio, immunoglobulin E, serum ferritin, and blood hemoglobin. After adjusting for covariates, no association was found between S-25(OH)D and the prevalence of CDs. Conclusion: Accumulated lower levels of S-25(OH)D among immigrants may impact their health profile in terms of CD-related biomarkers, which partially explains immigrants' health deterioration over time. We recommend further longitudinal research to investigate immigrants' vitD and health deterioration.
... [8][9][10] We matched two female controls from the RPDB who were alive on the corresponding immigrant's index date and not found in the IRCC database between 1986 to 2010, on year of birth. 13 We identified cases of invasive cervix cancer (ICD10 diagnosis code C53) from the Ontario Cancer Registry among immigrants and controls between the index date and December 31, 2014. All immigrants and controls were followed to date of last contact, date of cervix cancer diagnosis, or December 31, 2014-whichever came first. ...
... Because it was possible for the association between immigration status and hazard of invasive cervix cancer to change over time, we included an interaction between immigration status (immigrant or nonimmigrant) and time, where time was categorized into two intervals using the point of 10 years after index. 12,13 Analyses were conducted with SAS version 9.3 (SAS Institute, Inc, Cary, NC). All statistical tests were two-sided, and P values less than 0.05 were considered statistically significant. ...
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Background: The risk of invasive cervical cancer (ICC) varies throughout the world. We aimed to compare the risk of this invasive disease among immigrants arriving in Ontario with that of the general female population of Ontario. Methods: We used an exposure-control matched design. We identified females from the Immigration, Refugees, and Citizenship Canada (IRCC) database with arrival in Ontario, and whose first eligibility for the Ontario Health Insurance Plan according to its Registered Persons Database fell between July 1, 1991, and June 30, 2008, at age 20 years or older, and matched two female controls on year of birth. We identified cases of ICC between the index date and December 31, 2014. Crude rates and relative rates of ICC were calculated. Multivariable extended Cox regression models were then implemented. Results: The crude rate of ICC was 0.032 per 100 000 person-years for immigrants and 0.037 for controls. Immigrants who were born in certain countries showed a higher risk of ICC; Russia had a relative rate of 1.736 compared with a relative rate of 0.221 among those born in Iran. Among immigrants, the age-adjusted HR was 0.76 (95% CI 0.63-0.92) after 10 years of residency when compared with controls. Immigrants aged 20 to 39 years had a lower risk of ICC compared with controls of equivalent age, and immigrants aged ≥40 years had a higher risk of ICC. Conclusions: The risk of ICC among immigrants in Ontario varies by age, country of birth, and time since immigration.
... Our findings of higher ASIR in Canadian immigrant population, particularly in areas with significantly higher Hispanic composition (1.47, 95% CI 1.35-1.60) is aligned with the previous literature demonstrating higher rates on gastric cancer among immigrants in Ontario [59]. The Statistics Canada report showed a rapid growth of Hispanic Canadian population, by 32% between 1996 and 2001 [60]. ...
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Gastric cancer is the 5th most common malignancy worldwide, representing ~5–10% of all new cancer cases. Although its incidence is declining, it is estimated that 1 in 98 Canadians will develop gastric cancer in their lifetime. The epidemiology and distribution of gastric cancer throughout Canada, however, remains poorly understood. A retrospective analysis of demographic data across Canada between 1992 and 2010 was performed using 2 population-based cancer registries. The incidence of gastric cancer was examined at the levels of provinces, cities, and postal codes. In addition, 43,955 patients were diagnosed with gastric cancer in Canada between 1992 and 2010; 66% were male and the average age of diagnosis was 68.4 years. The age-adjusted incidence rate was 5.07 cases per 100,000 individuals per year. The incidence decreased over the study period by 30%. High incidence rates were identified in rural areas of Newfoundland and Labrador, New Brunswick, and Quebec. Our study found a significant association between gastric cancer incidence rates and lower socioeconomic status, as well as Hispanic ethnicity. This is the first study to provide a comprehensive analysis of the incidence of gastric carcinoma in Canada, identifying high-risk populations that may benefit from increased primary and secondary prevention.
... Paszat et al. [45] examined the relation between immigration status and colorectal cancer incidence in a exposurecontrol matched design study in Canada. Among female immigrants, the HR for colorectal cancer was 0.63 (95% CI 0.59, 0.67) during the first 10 years, and 0.66 (95% CI 0.59, 0.74) thereafter. ...
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Background Several social determinants of health have been examined in relation to colorectal cancer incidence, stage at diagnosis, and survival including income, education, neighborhood disadvantage, immigration status, social support, and social network. Colorectal cancer incidence rates are positively associated with income and other measures of socioeconomic status. In contrast, low socioeconomic status tends to be associated with poorer survival.Methods The present review is based upon bibliographic searches in PubMed and CINAHL and relevant search terms. Articles published in English from 1970 through April 1, 2019 were identified using the following MeSH search terms and Boolean algebra commands: colorectal cancer AND (incidence OR stage OR mortality) AND (social determinants OR neighborhood disadvantage OR racial discrimination OR immigration OR social support).ResultsThis review indicates that poverty, lack of education, immigration status, lack of social support, and social isolation play important roles in colorectal cancer stage at diagnosis and survival.Conclusions To address social determinants of colorectal cancer, effective interventions are needed that account for the social contexts in which patients live.
... At the same time, the present situation is alarming, as various population-based studies are depicting a steep increase in CRC incidence (Meyer and Are 2017). It is a matter of huge concern that the incidence rates are much higher in Indian immigrants to the UK and USA, signifying the role of living manners and food habits in causing CRC (Paszat et al. 2017). It infers that with the fiscal shift of India from developing to the developed economy, there will be much higher CRC cases. ...
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The present study was conducted to determine the prognostic significance of I655V SNP (rs1136201) is a genetic one in HER-2 oncoprotein in cases of colorectal cancer (CRC). We conducted a case–control study analysing 83 subjects (naïve primary CRC cases) who underwent CRC biopsy/colectomy and included 57 healthy control subjects. Analysis of HER-2 polymorphism was done by PCR-RFLP technique. The mean age was found to be 55.9 years; median age was 56 years and mode age was 54 years with a range of 43 (30–73). Males constitute 63 (75.9%) and females constitute 20 (24.1%) of patient population. According to gradewise distribution, 12 (14.45%) patients were of Grade I, 53 (63.85%) of Grade II, and 18 (21.68%) were of Grade III. We found out that out of 83 patients, 52 (62.65%) were of homozygous wild type (A/A; Ile/Ile); 27 (32.53%) were of heterozygous type (A/G; Ile/Val) and 4 (4.81%) were of homozygous mutant type (G/G; Val/Val). Allelic frequency of Ile (A) was found out to be 0.79 and that of Val (G) is 0.21 and were not significantly different from the healthy control population. Fischer’s exact p value obtained was 0.86.
... While there have been previous studies analyzing CRC incidence in the USA, these have mostly involved smaller source populations and were not specifically focused on the elderly (patients 75 years of age and older) [3,26,27]. Troisi et al. [3] analyzed the incidence of CRC within the USA from a source population of around 220,000 persons utilizing the US Surveillance, Epidemiology, and End Results Fig. 2 Five-year rate of new colorectal cancer diagnosis in the elderly (age 75 years and above) based on gender and race Fig. 3 Prevalence of colorectal cancer based on cancer location and age-group (SEER) Program, from 1975 to 1994, and found an overall CRC incidence of approximately 150-200 per 100,000 persons in both males and females 75 years of age and older, confirming the overall trend of CRC incidence increasing with age [3]. Although our study found a lower prevalence rate of first-ever CRC diagnosis in the elderly, it is important to note that the former study utilized a smaller source population and analyzed this population during a different time period, and given advances in CRC screening and awareness, it is logical that the incidence of CRC has decreased since the 1990s. ...
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Background/aims: There is a lack of studies describing the epidemiology of colorectal cancer (CRC) in patients aged 75 years and older (elderly). Current guidelines recommend against routine screening colonoscopies in this population. We sought to describe the epidemiology of CRC in the elderly, utilizing a large, population-based database as this may impact screening guidelines in this population. Methods: Utilizing a commercial database (Explorys Inc, Cleveland, OH), we identified a cohort of patients with a first-ever diagnosis of CRC between 2012 and 2017 based on the Systematized Nomenclature of Medicine-Clinical Terms. We calculated the rate of first-ever CRC occurrence in the elderly, described age, race, and gender-based rates of new CRC diagnoses, and identified associated conditions for new CRC in the elderly. Results: The rate of first-ever CRC in the elderly (aged 75 and above) was 102.6/100,000 persons. The rate of new CRC was higher in males than females and in African Americans than Caucasians and Asians. There was a higher prevalence of right than left colon cancer. The rate of new CRC was higher in elderly with certain comorbidities. Conclusion: The rate of new CRC diagnosis in the elderly was substantially greater compared to the overall population. Screening would be justified especially if a patient's life expectancy warrants it particularly if the patient has specific associated conditions that increase the risk for CRC.
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Objectives To evaluate the association between immigration status and all-cause mortality in different disease cohorts, and the impact of loss to follow-up on the observed associations. Design Population-based retrospective cohort study using linked administrative health data in Ontario, Canada. Setting We followed adults with a first-ever diagnosis of ischaemic stroke, cancer or schizophrenia between 2002 and 2013 from index event to death, loss to follow-up, or end of follow-up in 2018. Primary and secondary outcome measures Our outcomes of interest were all-cause mortality and loss to follow-up. For each disease cohort, we calculated adjusted HRs of death in immigrants compared with long-term residents, adjusting for demographic characteristics and comorbidities, with and without censoring for those who were lost to follow-up. We calculated the ratio of two the HRs and the respective CL using bootstrapping methods. Results Immigrants were more likely to be lost to follow-up than long-term residents in all disease cohorts. Not accounting for this loss to follow-up overestimated the magnitude of the association between immigration status and mortality in those with ischaemic stroke (HR of death before vs after accounting for censoring: 0.78 vs 0.83, ratio=0.95; 95% CL 0.93 to 0.97), cancer (0.74 vs 0.78, ratio=0.96; 0.95 to 0.96), and schizophrenia (0.54 vs 0.56, ratio=0.97; 0.96 to 0.98). Conclusions Immigrants to Canada have a survival advantage that varies by the disease studied. The magnitude of this advantage is modestly overestimated by not accounting for the higher loss to follow-up in immigrants.
Article
Objective To evaluate the association between immigration status and stroke incidence. Methods We conducted a retrospective cohort study of 8 million adults (15% immigrants) residing in Ontario, Canada on January 1, 2003, with no history of prior stroke or transient ischemic attack (TIA). Subjects were followed until March 31, 2018 to identify incident stroke or TIA, defined as hospitalization or emergency room visit. We calculated adjusted hazard ratios (HR) of stroke or TIA in immigrants compared to long-term residents using cause-specific hazard models, adjusting for demographics and comorbidities. We evaluated whether the association varied by age, stroke type or country of origin of immigrants. Results During 109 million person-years follow-up, we observed 235,336 incident stroke or TIA events. Compared to long-term residents, immigrants had a lower rate of stroke or TIA (10.9 vs. 23.4 per 10,000 person-years, HR 0.67; 0.66-0.68). This was true across all age groups and stroke types, with a HR in immigrants vs. long-term residents for ischemic stroke of 0.71 (0.69-0.72), intracerebral hemorrhage 0.89 (0.85-0.93), subarachnoid hemorrhage 0.85 (0.81-0.91), and TIA 0.53 (0.51-0.54). The magnitude of the reduction in stroke risk associated with immigration status was less pronounced in immigrants from the Caribbean (HR 0.95; 0.91-1.00), Latin America (HR 0.85;0.82-0.91) and Africa (HR 0.80; 0.74-0.85) than in those from other world regions. Conclusions Immigrants have a lower rate of stroke or TIA than long-term residents with variation by age, stroke type and country of origin. This knowledge may be useful for developing targeted primary stroke prevention strategies.
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The rate of cancer screening is generally increasing in the US. In Minnesota, the statewide average rate of screening for colorectal cancer (CRC) is 73%. However, screening completion is relatively low among Somali men; overall, only 27% of Somali immigrants have been screened for CRC. Factors contributing to this disparity have not been well researched. The purpose of this pilot study was to employ focus group methodology to describe and advance understanding of the barriers and enablers associated with CRC screening among Somali men ages 50–74 in Minnesota. Three focus groups were conducted among 27 Somali men in Minnesota. A 9-question, semi-structured interview guide was used. The sessions were audio recorded, transcribed verbatim, and checked for accuracy by research staff prior to data analysis. Three research team members utilized the constant comparative method and NVivo to conduct data analysis. Five barriers to CRC screening emerged from the analyses: (1) lack of knowledge, (2) emotional barriers, (3) acculturation, (4) accountability, and (5) fatalistic beliefs. In addition, two factors enabling CRC screening and prevention emerged: the need for tailored interventions and preventive lifestyle behaviors. The insights gained from this research will assist in developing health promotion and education-focused interventions that encourage Somali immigrants in Minnesota and beyond to seek early detection screening for CRC. Abbreviations: CRC: Colorectal Cancer; FIT: Fecal Immunochemical Test; FOBT: Fecal Occult Blood Test; FQHC: Federally Qualified Health Center; PA: Project Assistant; PI: Principal Investigator
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Background Historically, studies suggested that immigrants acquire the risk of colorectal cancer (CRC) as US-born persons within the same generation. CRC risk of immigrants is largely unknown in this era of cancer screening and widespread immigration. We investigated the association of place of birth and cancer beliefs with uptake of CRC screening. Methods The 2007 Health Information National Trends Survey was used and 4,299 respondents (weighted population size=81,896,392) who were 50 years and older (3,960 US-born and 339 foreign-born) were identified. We defined being current with CRC screening guidelines as the use of fecal occult blood test within 1 year, sigmoidoscopy within 5 years, or colonoscopy within 10 years. We compared being up-to-date with CRC screening among foreign-born versus US-born respondents. Logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (CI). Results Overall, 2,594 (63.3%) US-born and 208 (52.8%) foreign-born respondents were current with CRC screening. Foreign-born respondents were less current in unadjusted model (OR 0.65; 95% CI: 0.50-0.85) but became non-statistically significant after adjustment (OR 0.79; 95% CI: 0.51-1.24). Respondents who believed that screening finds cancer when it is easy to treat (OR 2.85; 95% CI: 1.44-3.61), those who believed that cancer can be cured when detected early (OR 1.56; 95% CI: 1.20-2.00), and those who worry about getting cancer (OR 1.34; 95% CI: 1.10-1.61) were likely to be current with CRC screening. However, respondents with fatalistic beliefs were borderline less likely to be current (OR 0.82; 95% CI: 0.65-1.04). Conclusion There is a need to improve education on CRC screening, particularly among foreign-born adults.
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Background Colorectal cancer is the third most common cancer in Iran. The increasing trend of colorectal cancer incidence in Iran and the close relationship with the geographical location are the underlying reasons for this study. Methods Data source: Eleven databases, including MEDLINE, EMBASE, SCOPUS, and four other databases, for articles in Persian were searched from April 2014 to October 2014. Additional data were obtained from an online survey of the Central Library of Tabriz Faculty of Medicine. Study eligibility criteria: In this systematic review and meta-analysis, we included studies reporting different measures of incidence, age-standardized incidence rates, and crude incidence rates. All rates (per 100,000 person-years) were standardized to the world standard population. Study appraisal and synthesis methods: A preliminary review of the title and abstracts of these articles was used to exclude any that were clearly irrelevant. The full text review determined whether the article was relevant to our topic. All the potentially relevant manuscripts were reviewed by two other investigators (S.D., M.G.). A total of 39 studies (10 Persian and 29 English articles) from different provinces and diverse areas of Iran, were analyzed in this study using comprehensive meta-analysis software. For accuracy studies, we used estimated rates for males and females with 95 % confidence intervals. Results Age-standardized incidence rates were obtained based on the random effects model and were 8.16 (95 % CI: 6.64 to 9.68) and 6.17 (95 % CI: 5.01 to 7.32) for males and females, respectively. The random crude rates were 5.58 (95 % CI: 4.22 to 6.94) for males and 4.01 (95 % CI: 3.06 to 4.97) for females. Conclusions Colorectal cancer incidence rates rise due to individual and environmental risk factors as well as improvement in the registry system and increase in access to health services. A more executed organized and structured system for collecting cancer data, in all cities and rural areas of the country, is an essential priority.
Article
Colorectal cancer is currently the third deadliest cancer in the United States and will claim an estimated 49,190 U.S. lives in 2016. The purpose of this review is to summarize our current understanding of this disease, based on nationally published statistics and information presented in peer-reviewed journal articles. Specifically, this review will cover the following topics: descriptive epidemiology (including time and disease trends both in the United States and abroad), risk factors (environmental, genetic, and gene-environment interactions), screening, prevention and control, and treatment. Landmark discoveries in colorectal cancer risk factor research will also be presented. Based on the information reviewed for this report, we suggest that future U.S. public health efforts aim to increase colorectal cancer screening among African American communities, and that future worldwide colorectal cancer epidemiology studies should focus on researching nutrient-gene interactions towards the goal of improving personalized treatment and prevention strategies.
Article
Objective: To investigate overall colorectal cancer (CRC) screening rates, patterns in the use of types of CRC screening, and sociodemographic characteristics associated with CRC screening; and to gain insight into physicians' perceptions about and use of fecal occult blood testing [FOBT] and colonoscopy for patients at average risk of CRC. Design: Mixed-methods study using cross-sectional administrative data on patient sociodemographic characteristics and semistructured telephone interviews with physicians. Setting: Toronto, Ont. Participants: Patients aged 50 to 74 years and physicians in family health teams in the Toronto Central Local Health Integration Network. Main outcome measures: Rates of CRC screening by type; sociodemographic characteristics associated with CRC screening; thematic analysis using constant comparative method for semistructured interviews. Main findings: Ontario administrative data on CRC screening showed lower overall screening rates among those who were younger, male patients, those who had lower income, and recent immigrants. Colonoscopy rates were especially low among those with lower income and those who were recent immigrants. Semistructured interviews revealed that physician opinions about CRC screening for average-risk patients were divided: one group of physicians accepted the evidence and recommendations for FOBT and the other group of physicians strongly supported colonoscopy for these patients, believing that the FOBT was an inferior screening method. Physicians identified specialist recommendations and patient expectations as factors that influenced their decisions regarding CRC screening type. Conclusion: There was considerable variation in CRC screening by sociodemographic characteristics. A key theme that emerged from the interviews was that physicians were divided in their preference for FOBT or colonoscopy; factors that influenced physician preference included the health care system, recommendations by other specialists, and patient characteristics. Providing an informed choice of screening method to patients might result in higher screening rates and fewer disparities. Changes in policy and physician attitudes might be needed in order for this to occur.
Article
Colorectal cancer is a major public health problem, being the third most commonly diagnosed cancer and the fourth cause of cancer death worldwide. There is wide variation over time among the different geographic areas due to variable exposure to risk factors, introduction and uptake of screening as well as access to appropriate treatment services. Indeed, a large proportion of the disparities may be attributed to socioeconomic status. Although colorectal cancer continues to be a disease of the developed world, incidence rates have been rising in developing countries. Moreover, the global burden is expected to further increase due to the growth and aging of the population and because of the adoption of westernized behaviors and lifestyle. Colorectal cancer screening has been proven to greatly reduce mortality rates that have declined in many longstanding as well as newly economically developed countries. Statistics on colorectal cancer occurrence are essential to develop targeted strategies that could alleviate the burden of the disease. The aim of this paper is to provide a review of incidence, mortality and survival rates for colorectal cancer as well as their geographic variations and temporal trends.
Article
Background: Colorectal cancer screening programmes in Italy invite 50-69-year-old residents for a faecal immunochemical test every two years, regardless of their citizenship. Methods: The 2013 National Survey on Italian colorectal cancer screening programmes compared immigrants born in low- or middle-income countries with subjects who were born in Italy, by collecting aggregated data on compliance, faecal immunochemical test results, compliance with colonoscopy, detected lesions and stage at diagnosis separately for Italians and immigrants. Results: Overall, 85 screening programmes invited 3,292,451 subjects, of whom 192,629 had been born abroad (5.9%). Compliance with invitation was lower in immigrants (34.3% vs. 51.3% in Italians), with p<0.001. Compliance was higher in females, regardless of the country of birth, in the youngest age group of immigrants but in the oldest of Italians. Immigrants showed a borderline excess of standardised faecal immunochemical test positivity rate at first screening (5.4% vs. 5.1% in Italians, p=0.05) and a significant excess at repeat screenings (4.8% vs. 4.4%, p=0.002). The detection rates for carcinoma and advanced adenomas were lower in immigrants than in Italians at first screening (respectively 1.34‰ vs. 1.62‰ and 8.41‰ vs. 9.25‰) - although the differences were not statistically significant - but not at repeat screening (respectively 1.06‰ vs. 0.98‰ and 6.90‰ vs. 6.79‰). Conclusions: Migrants showed a lower compliance with screening than Italians. The prevalence of neoplasia was lower at first screening and similar to the Italians' at repeat screenings.
Article
Asian Americans are now the most rapidly growing minority group in the USA. Over 60 % of Asian Americans in the USA are immigrants. Cancer has been the leading cause of death among Asian Americans since 1980. Understanding the barriers to screening is essential to reduce the unnecessary burden of cancer. Little is known about colorectal cancer screening behavior among foreign-born Asian Americans and how socio-demographic factors may influence the behavior. Even less is known about disaggregated Asian subgroups. Using data from the Chicago Asian Community Survey, a local health assessment survey of three Asian subgroups in Chicago, Chinese, Cambodian, and Vietnamese, this study found that the colorectal cancer screening rate were much lower among foreign-born Asian Americans in Chicago (30 %) than the national rate for the general population (59 %). Furthermore, we studied disaggregated data to determine colorectal cancer screening differences between communities. Findings from this study provide a critical evidence base to inform future research and intervention designs.
Article
In the province-wide colorectal cancer (CRC) screening program in Ontario, Canada, individuals with a family history of CRC are offered colonoscopy screening and those without are offered guaiac fecal occult blood testing (gFOBT, Hemoccult II). We used microsimulation modeling to estimate the cumulative number of CRC deaths prevented and colonoscopies performed between 2008 and 2038 with this family history-based screening program, compared to a regular gFOBT program. In both programs, we assumed screening uptake increased from 30% (participation level in 2008 before the program was launched) to 60%. We assumed that 11% of the population had a family history, defined as having at least one first-degree relative diagnosed with CRC. The programs offered screening between age 50-74 years, every two years for gFOBT, and every ten years for colonoscopy. Compared to opportunistic screening (2008 participation level kept constant at 30%), the gFOBT program cumulatively prevented 6,700 more CRC deaths and required 570,000 additional colonoscopies by 2038. The family history-based screening program increased these numbers to 9,300 and 1,100,000, a 40% and 93% increase, respectively. If biennial gFOBT was replaced with biennial fecal immunochemical test (FIT), annual Hemoccult Sensa or five-yearly sigmoidoscopy screening, both the added benefits and colonoscopies required would decrease. A biennial gFOBT screening program that identifies individuals with a family history of CRC and recommends them to undergo colonoscopy screening would prevent 40% (range in sensitivity analyses: 20-51%) additional deaths while requiring 93% (range: 43-116%) additional colonoscopies, compared to a regular gFOBT screening program. This article is protected by copyright. All rights reserved. © 2014 Wiley Periodicals, Inc. © 2015 UICC.
Article
Colorectal cancer (CRC) is an important cause of mortality and morbidity in North America. Screening using a fecal occult blood test, flexible sigmoidoscopy, or colonoscopy reduces CRC mortality through the detection and treatment of precancerous polyps and early stage CRC. Although CRC screening participation has increased in recent years, large inequities still exist. Minorities, new immigrants, and those with lower levels of education or income are much less likely to be screened. This review provides an overview of the commonly used tests for CRC screening, disparities in CRC screening, and promising methods at the individual, provider, and system levels to reduce these disparities. Overall, to achieve high CRC participation rates and reduce the burden of CRC in the population, a multi-faceted approach that uses strategies at all levels to reduce CRC screening disparities is urgently required.