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Clinical subtypes of breast cancer in Thai women: a population-based study of Chiang Mai province

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Background The change over time of distribution of breast cancer subtypes using population-based data has not been reported. Objective To describe the change over time of the distribution of female breast cancer by clinical subtype among the population in Chiang Mai, Thailand. Methods Data of breast cancer patients from Chiang Mai Cancer Registry, diagnosed from 2004 to 2013 were combined with immunohistochemical status from medical record, and used to describe the proportions of clinical breast cancer subtypes: (1) luminal A-like (ER+/PR+ and HER2-), (2) luminal B-like (ER+/PR+ and HER2+), (3) HER2 (ER- and PR- and HER2+), (4) triple-negative (ER- and PR- and HER2-). The distribution of breast cancer subtypes by age group was also described. Results Among 3,228 female breast cancer cases diagnosed during 2004–2013, the median age was 52 years and most patients presented at the regional stage. The unknown tumor subtype was lower than 25% in the periods 2008– 2009, 2010–2011, and 2012–2013. In those periods, the proportions of luminal A-like were 33%, 36%, and 48%; the proportions of luminal B-like were 14%, 20%, and 16%, the proportions of HER2 were 15%, 14%, and 13%; and the proportions of triple-negative were 16%, 14%, and 13%, respectively. In comparison with other groups, women aged ≥60 years had a significantly higher proportion of luminal A-like ( P = 0.001), while women aged <40 years tended to have a higher proportion of triple-negative ( P = 0.10). Conclusions The proportion of breast cancer with luminal subtypes is increasing. Thus, in the future, treatment protocols with a variety of hormone therapies should be provided in order to improve efficacy and coverage of treatment for this population.
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DOI ./abm-- — Asian Biomed (Res Rev News) ; ():–
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Brief communication (original)
Clinical subtypes of breast cancer in Thai women:
a population-based study of Chiang Mai province
Patumrat Sripan,,, Hutcha Sriplung, Donsuk Pongnikorn, Surichai Bilheem, Shama Virani,
Narate Waisri, Chirapong Hanpragopsuk, Puttachart Maneesai, Panrada Tansiri,
Imjai Chitapanarux,,,*
Abstract
Background: The change over time of distribution of breast cancer subtypes using population-based data has not been
reported.
Objective: To describe the change over time of the distribution of female breast cancer by clinical subtype among the
population in Chiang Mai, Thailand.
Methods: Data of breast cancer patients from Chiang Mai Cancer Registry, diagnosed from 2004 to 2013 were
combined with immunohistochemical status from medical record, and used to describe the proportions of clinical
breast cancer subtypes: (1) luminal A-like (ER+/PR+ and HER2-), (2) luminal B-like (ER+/PR+ and HER2+),
(3) HER2 (ER- and PR- and HER2+), (4) triple-negative (ER- and PR- and HER2-). The distribution of breast cancer
subtypes by age group was also described.
Results: Among 3,228 female breast cancer cases diagnosed during 2004–2013, the median age was 52 years and
most patients presented at the regional stage. The unknown tumor subtype was lower than 25% in the periods 2008–
2009, 2010–2011, and 2012–2013. In those periods, the proportions of luminal A-like were 33%, 36%, and 48%; the
proportions of luminal B-like were 14%, 20%, and 16%, the proportions of HER2 were 15%, 14%, and 13%; and the
proportions of triple-negative were 16%, 14%, and 13%, respectively. In comparison with other groups, women aged
60 years had a significantly higher proportion of luminal A-like (P = 0.001), while women aged <40 years tended to
have a higher proportion of triple-negative (P = 0.10).
Conclusions: The proportion of breast cancer with luminal subtypes is increasing. Thus, in the future, treatment
protocols with a variety of hormone therapies should be provided in order to improve efficacy and coverage of treatment
for this population.
Keywords: age groups; breast neoplasms; women
*Correspondence to: Imjai Chitapanarux, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai , Thailand,
e-mail: imjai.chitapanarux@cmu.ac.th
Northern Thai Research Group of Radiation Oncology (NTRG-RO), Faculty of Medicine, Chiang Mai University, Chiang Mai , Thailand
Chiang Mai Cancer Registry, Faculty of Medicine, Chiang Mai University, Chiang Mai , Thailand
Research Institute for Health Sciences, Chiang Mai University, Chiang Mai , Thailand
Epidemiology Unit, Faculty of Medicine, Prince of Songkla University, Songkhla , Thailand
Cancer Registry Unit, Lampang Cancer Hospital, Lampang , Thailand
Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai , Thailand
Open Access. © 2019 Patumrat Sripan et al., published by Sciendo. This work is licensed under the Creative
Commons Attribution NonCommercial-NoDerivatives 4.0 License.
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 P. Sripan et al.
Breast cancer is the most common cancer among women glo-
bally [1]. There were approximately 1.7 million reported cases
of breast cancer and 0.5 million deaths in women worldwide
according to the GLOBOCAN 2012 released by the Interna-
tional Agency of Research on Cancer (IARC) [2]. The age-
standardized incidence rate (ASR) was 28.5 per 100,000 in
Thai women based on data collected during 2010–2012 [3]. In
northern Thailand, the incidence of breast cancer continues to
increase [4]. Similarly, in the Chiang Mai population, our pre-
vious study showed that female breast cancer incidence rates
increased from an ASR of 14.8 per 100,000 women-years in
1989 to 32.9 cases per 100,000 women-years in 2013. The
incidence rate of female breast cancer increased at an APC
of 3.1% (95% confidence interval [CI]: 2.6%, 3.7%). From
projections, we found that the highest incidence might reach
an ASR of 36.7 per 100,000 women-years in the next decade
and the incidence in elderly females tend to be higher than the
middle-aged females [5]. Breast cancer was responsible for
nearly 5,092 deaths among Thai women in 2012 [6]. The clini-
cal subtype of the breast cancer has become an important con-
sideration in treatment decision making. In conjunction with
conventional clinical factors such as tumor size and grade,
lymph node involvement and surgical margins, the molecular
classification of the tumor provides prognostic information for
the heterogeneous disease of breast cancer [7].
Clinical subtype distribution has varied in different age
groups, luminal-A subtype was likely to have higher propor-
tion in the elderly group compared to other groups. Whereas,
the proportion of triple-negative was highest in young age
group compared to other groups [8, 9]. Aging plays an impor-
tant role on incidence and also the efficacy of treatment. Cli-
nical subtype of breast cancer by age group may be useful for
treatment and facility provision.
A number of hospital-based studies have reported the
proportion of breast cancer subtypes based on estrogen recep-
tor (ER)/progesterone receptor (PR) and/or human epidermal
growth factor receptor 2 (HER2) status in Thai women [10–
12]. However, the change over time of distribution of breast
cancer subtypes using population-based data has not been
reported. Therefore, our study describes the distribution of
breast cancer subtypes over the period from 2004 to 2013 in
the Chiang Mai population in Northern Thailand.
Materials and methods
The data used in this study are retrospective data from the
cancer registry and the study was approved by the Research
Ethics Committee of the Faculty of Medicine, Chiang Mai
University (certificate of approval no. 316/2016).
This observational study extracted data of women dia-
gnosed with breast cancer during 2004–2013 and living in
Chiang Mai province were collected by the Chiang Mai Cancer
Registry using International Classification of Diseases–10th
edition (ICD-10) codes C50. The Chiang Mai Cancer Registry
is a population-based cancer registry operating in the Maharaj
Nakorn Chiang Mai Hospital, Faculty of Medicine, Chiang Mai
University. The data were collected from all hospitals in Chiang
Mai, including Maharaj Nakorn Chiang Mai Hospital, which is
a university hospital, as well as government hospitals, muni-
cipal hospitals, private hospitals, and community hospitals.
Patient data were systematically collected and carefully verified
by cancer registry personnel and using cancer registry software
(CanReg5). Cancer registry data included patient profiles, such
as date of birth, age at diagnosis, clinical diagnosis, patholo-
gical report, clinical extent of disease before treatment, and
initial treatment. Immunohistochemical (IHC) status including
ER, PR, and HER2 was extracted from the medical record.
The stage of breast cancer was categorized based on the
extent of disease of cancer. Localized tumors are restricted to the
breast, regional tumors involve axillary lymph nodes, and distant
stage involves spreading of cancer to other parts of the body.
Classification of clinical breast cancer subtype
ER, PR count as positive when the percentage of cells with
nuclear positivity was found at least 1% and HER2 count as
positive when the percentage of cells with uniform intense
complete membrane staining was found at least 1%. The
four clinical subtypes are based on the presence or absence
of molecular markers, including ER, PR, and HER2 [13, 14].
Luminal A-like is characterized by ER-positive (+) and/or
PR+ and HER2 negative (-) status. Luminal B-like subtype
is distinguished by ER+ and/or PR+ and HER2+ status. The
HER2 subtype is characterized by HER2+, ER-, and PR-.
Triple-negative subtypes are negative for all three markers
(ER-, PR-, and HER2-).
Statistical analysis
The proportions of clinical subtype of breast cancer were
described in 2-year periods from 2004 to 2013. Trend of pro-
portion was examined using c2 test for trend in proportion
and trend of median age were examined using Mann–Kendall
trend test. Frequency distributions of breast cancer subtypes
by age, stage at diagnosis, and diagnosis year were calculated.
A c2 test was used to compare distributions using Stata version
11 (StataCorp LP, College Station, TX, USA).
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Clinical subtypes of breast cancer in Thai women Asian Biomed (Res Rev News) 2019; 13(1):11–17
Analyses were conducted for all females, young age
group (<40 years), middle-aged group (40–59 years), and
elderly group (60 years) to determine the distribution of
breast cancer subtype by age group.
Visually illustrate trends and trends test were conducted
using R program. All reported P are two-sided values and
P < 0.05 was considered statistically significant.
Results
Distributions of clinical subtypes by patient characteristics
Among the 3,228 female breast cancer cases with an overall
median age of 52 years (interquartile range, IQR: 45–60) dia-
gnosed during 2004–2013, 25%, 66%, 7%, and 2% had loca-
lized stage, regional stage distant stage, and unknown stage,
respectively, at diagnosis. Table 1 shows the characteristics of
patients at diagnosis over time (2004–2013). In women with
known subtypes, the distributions of clinical subtypes were
significantly different by age group, stage, and year of diag-
nosis (Table 2).
Change of proportion of breast cancer subtypes over time
In 2-year period, the proportion of unknown tumor subtype
dramatically declined from 65% in 2004–2005 to 9% in
2012–2013. In the most recent three periods, 2008–2009,
2010–2011, and 2012–2013, in which the unknown tumor
subtype was lower than 25%, the proportion of luminal A-like
was 33%, 36%, and 48% (P < 0.001); the proportion of luminal
B-like was 14%, 20%, and 16% (P = 0.2); the proportion of
HER2 was 15%, 14%, and 13% (0.24); and the proportion of
triple-negative was 16%, 14%, and 13% (0.11), respectively
(Figure 1).
Proportion of breast cancer subtypes by age group
Among the 2,340 breast cancer patients with known clinical
subtype, the most common subtype found in all age groups
was luminal A-like. Overall, the proportion of luminal A-like,
luminal B-like, HER2, and triple-negative was 46%, 20%,
16%, and 18%, respectively. The elderly group had a signi-
ficantly higher proportion of luminal A-like (52%) compa-
red to the other groups: 45% in the middle-aged group and
38% in the young age group (P = 0.001). The proportion of
triple-negative was higher in the young age group (22%) than
in other groups: 17% in the middle-aged group and 19% in
the elderly group, but this was not significantly different
(P = 0.10). The proportions of luminal B-like were 26%,
20%, and 16% in the young age, middle-aged, and elderly
groups, respectively. The proportions of HER2 tumors were
14%, 18%, and 13% in the young age, middle-aged, and
elderly groups (Table 1).
Table .Characteristics of patients at diagnosis over time (–)
Total, n (%) Year of diagnosis Pa
2004–2005 2006–2007 2008–2009 2010–2011 2012–2013
Number of patients 3,228 (100) 530 (17) 571 (18) 668 (21) 656 (20) 803 (25)
Age (years)
Median (IQR) 45 (52–60) 50 (44–58) 51 (44–59) 51 (45–58) 53 (46–60) 54 (47–61) 0.043b
<40 349 (11) 63 (12) 76 (13) 67 (10) 72 (11) 71 (9) 0.02
40–59 2,072 (64) 346 (65) 358 (63) 465 (70) 401 (61) 502 (62) 0.20
60 807 (25) 121 (23) 137 (24) 136 (20) 183 (28) 230 (29) 0.002
Stage
Localized 794 (25) 125 (24) 132 (23) 156 (23) 155 (24) 226 (28) 0.04
Regional 2,131 (66) 352 (66) 390 (68) 462 (69) 447 (68) 480 (60) 0.02
Distant 235 (7) 38 (7) 39 (7) 44 (7) 49 (8) 65 (8) 0.39
Unknown 68 (2) 15 (3) 10 (2) 6 (1) 5 (1) 32 (4) 0.17
IQR, Interquartile range.
ac test for trend in proportions.
bMann–Kendall trend test.
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 P. Sripan et al.
of luminal subtype (ER+ and/or PR+) has been increasing,
particularly the proportion of luminal A-like (ER+ or PR+
and HER2-). The proportion of HER2 (ER- and PR- and
HER2+) subtypes and triple-negative subtypes (ER- and PR-
and HER2-) were stable and lower than 20%.
Only a few studies previously reported on the proportion
of breast cancer subtypes based on ER/PR and HER2 in the
Thai population.
First, a study of patients with invasive ductal carcinomas
in Siriraj Hospital reported the proportion of female breast
cancer clinical subtypes [10]. Compared to the Siriraj Hos-
pital study, which assessed 324 breast cancer patients diag-
nosed during 2009–2010, our study found a lower proportion
of luminal A-like in our population in 2009–2010 (39% in our
study vs. 59% in the Siriraj study), but a higher proportion
of luminal B-like and HER2 (22% and 21%, respectively, in
our study vs. 12% and 13%, respectively, in the Siriraj Hos-
pital study). However, the proportion of triple-negative in our
population was similar to that reported in the Siriraj Hospital
study, 18% vs 15%.
Table .Distribution of breast cancer subtypes by age, stage and year of diagnosis (–)
Number of patients (%) Subtypes Pa
Luminal A-like
1,074 (46)
Luminal B-like
469 (20)
HER2
375 (16)
Triple-negative
422 (18)
Age (years) <0.001
<40 97 (38%) 66 (26%) 36 (14%) 57 (22%)
40–59 681 (45%) 309 (20%) 264 (18%) 256 (17%)
60 296 (52%) 94 (16%) 75 (13%) 109 (19%)
Stage <0.001
Localized 351 (55%) 100 (16%) 81 (13%) 100 (16%)
Regional 636 (42%) 334 (22%) 253 (17%) 297 (19%)
Distant 72 (44%) 31 (19%) 38 (23%) 24 (14%)
Unknown 15 (65%) 4 (17%) 3 (13%) 1 (5%)
Year of diagnosis <0.001
2004 35 (38%) 22 (24%) 19 (21%) 15 (17%)
2005 32 (33%) 20 (21%) 20 (21%) 24 (25%)
2006 76 (45%) 35 (21%) 20 (12%) 38 (22%)
2007 93 (48%) 37 (19%) 24 (13%) 38 (20%)
2008 128 (50%) 35 (14%) 40 (16%) 53 (20%)
2009 91 (34%) 56 (21%) 60 (23%) 57 (22%)
2010 109 (44%) 55 (22%) 48 (19%) 38(15%)
2011 124 (42%) 77 (26%) 41 (14%) 51 (18%)
2012 175 (51%) 77 (22%) 50 (14%) 45 (13%)
2013 211 (55%) 55 (14%) 53 (14%) 63 (17%)
ac test.
Figure .Distribution of breast cancer subtypes in all age groups over
-year period from  to 
Discussion
According to the population-based cancer registry data for
the Chiang Mai population in 2004–2013, the incidence of
breast cancer significantly increased [5]. While the propor-
tion of unknown subtype has been decreasing, the proportion
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Clinical subtypes of breast cancer in Thai women Asian Biomed (Res Rev News) 2019; 13(1):11–17
Second, a study of the northeastern Thailand popula-
tion on 294 patients diagnosed with breast cancer at Sri-
nagarind Hospital [12] from January 2004 to June 2006
found that the proportion of luminal A-like (ER+ or PR+
and HER2-), luminal B-like (ER+ or PR+ and HER2+),
HER2 (ER- and PR- and HER2+) and triple-negative was
51%, 8%, 19%, and 22%, respectively. Compared to the
Srinagarind Hospital study, our study found a slightly lower
proportion of luminal A-like (40% vs. 51%) but a signifi-
cantly higher proportion of luminal B-like (22% vs. 8%).
The proportions of HER2 and Triple-negative in our study
(17% and 22%, respectively) were similar to that in the Sri-
nagarind Hospital study.
The most recent study in southern Thailand [15] repor-
ted, 46%, 28%, 13%, and 13%, respectively, of the subtypes
luminal A-like, luminal B-like, HER2, and triple-negative
subtypes among 635 female breast cancer patients for whom
clinical subtype information was available in 2010–2012. The
proportion of luminal A-like in our study was the same as the
southern Thailand study. The proportion of luminal B-like was
lower in our study (24%), while the proportions of HER2 and
triple-negative in our study (16% and 15%, respectively) were
slightly higher than the southern Thailand study. A Western-
based population study using data of female breast cancer
cases diagnosed during 1999–2003 in California, showed a
12% proportion of triple-negative tumors. Women with triple-
negative breast cancers were significantly more likely to be
under age 40 [8]. Another larger study based on data from 17
population-based cancer registries that participate in the SEER
program in the United States reported that among 50,571 cases
in patients diagnosed in 2010, 73% were luminal A-like (HR+/
HER2-), 12% were triple-negative (HR-/HER2-), 10% were
luminal B-like (HR+/HER2+), and 5% were HER2 (HR-/
HER2+). This study also showed that the proportion of triple-
negative tumors was significantly higher in women age <65
[9]. The distribution of female breast cancer subtypes in the
US population and our Chiang Mai population are different.
The proportion of luminal A-like was much higher and HER2
was moderately lower in the US population compared to our
Chiang Mai population, but the distribution of our population
was likely closer to other studies among the Thai population
[10, 12, 15], despite that these Thai studies were not popu-
lation-based study and were conducted in different parts of
Thailand. Therefore, the distributions of female breast cancer
by subtypes using population-based data in different parts of
Thailand are recommended.
As reported in several studies [8, 9], our study found
similar results that the most common subtype in all age groups
was luminal A-like, which was likely to have a higher pro-
portion in the elderly group compared to other groups. Our
previous study showed a significant increase of breast cancer
incidence in the elderly [6]; in the present study, we also found
the increase of median age over time (Table 1). This might
explain the larger proportion of luminal A-like subtype over
time (Figure 1).
Moreover, an association between mammographic scree-
ning and detection of breast cancer with hormone positive,
that is, ER+ has been shown [16, 17]. In the present study,
percentage of localized tumor has been significantly increa-
sed (P = 0.04) and may represent the increased coverage of
screening. Although organized mammographic screening has
not been established in Thailand, the percentage of coverage
increased in different regions of the country. According to the
National Health and Welfare Survey in 2007 and the Repro-
ductive Health Survey in 2009 [18], the screening coverage
was found to be stable in Bangkok (13%) with moderate incre-
ase in the North, Northeast, and South (from 4% to 9%, 5% to
9%, and 7% to 10%, respectively). The coverage of mammo-
graphic screening was highest in Bangkok, followed by the
South region [18]. This might explain the higher proportion
of luminal subtypes in Bangkok and the South compared to
our Chiang Mai population, but our results were similar to
what was found in the Northeast in the corresponding period
of study.
IHC analyses including ER, PR, HER2, and Ki-67, define
the luminal A, luminal B, HER2, and Basal-like subtypes
[19]. However, our study only used ER, PR, and HER2 status
to classify clinical subtype of breast cancer because Ki-67
information is not routinely collected and was unavailable.
Therefore, we used the available IHC status to approximate
the breast cancer subtype into the four subtypes: luminal
A-like, luminal B-like, HER2, and triple-negative. However,
we found this distribution of approximated subtypes of breast
cancer using IHC was similar to what was reported in an
Asian-population study that was based on molecular data [20],
in which the luminal subtypes (luminal A+luminal B), HER2,
and triple-negative subtypes were 65%, 14%, and 13%, res-
pectively. Thus, this IHC classification may be more precise
in distinguishing breast cancer subtypes if the luminal A-like
and luminal B-like subtypes are merged into a single luminal
subtype.
At the beginning period of our study, HER2 status that
was necessary for IHC classification was not routinely exa-
mined. Therefore, clinical subtypes were not able to classify
in such periods in this population. This can lead to an unde-
restimation of the proportion of clinical subtypes. However,
age distribution of unknown subtype was not significantly
different from known subtype (P = 0.6). Fortunately, in
recent years, subtypes of breast cancer have been classified
more accurately with less unknown subtype. The change
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 P. Sripan et al.
of subtype distribution overtime could be more accurately
determined to observe the most three recent periods, which
had <25% unknown subtype.
Moreover, our study has lack of tumour, node, metasta-
sis (TNM) staging data defined by American Joint Committee
on Cancer (AJCC) because of incomplete staging from some
sources of data. The extent of disease which is commonly
applied for population-based cancer registry data was there-
fore used instead.
Another limitation of our study is the delay of data
collection. These are population-based data with active
method of collection which has delay time around 2 years.
Some additional time was spent for IHC status review of
all individual record from all hospitals in Chiang Mai pro-
vince because these data were not routinely collected by the
cancer registry. Inclusion of these essential clinical data in
the cancer registry would be encouraged for less time delay.
However, our study is the first population-based study that
describes the proportions of female breast cancer by clinical
subtype and the change over time of those proportions in the
Thai population. Moreover, this population-based data were
collected by the active method, so we consider the data to be
generally high quality, with more than 95% having histology
verification (%HV) and <1% is death certificate only cases
(%DCO).
As found in the results of hospital-based studies [10, 12,
15], the proportions of clinical subtypes of breast cancer were
different in different parts of Thailand. Thus, the trends in inci-
dence of breast cancer by clinical subtypes are likely to be
different between sets of regions. In the future, when the clas-
sification of clinical subtype of breast cancer could become
more stably accurate, the incidence estimation of female breast
cancer by clinical subtypes using population-based data from
different parts of Thailand is encouraged to determine the dis-
tribution of clinical subtype nationally and sub-nationally. The
results of our study may guide for the better treatment plan
considering the breast cancer subtypes. Since the proportion of
hormone positive subtypes has been increasing, the inclusion
of treatment facilities with a variety of hormone therapies as
essential medicines for universal health coverage should be
considered.
Conclusion
In the last decade, increased ability to identify subtypes has led
to better treatment planning. Although the proportion of breast
cancer with HER2 and triple-negative subtypes has remained
stable at <20% in our population, anti-HER2 therapies should
be made available. The proportion of hormone positive subty-
pes, luminal A-like, and luminal B-like has been increasing.
Therefore, in the future, treatment facilities with a variety of
hormone therapies should be provided in order to improve the
efficacy and coverage of treatment for this population.
Author contributions. PS, HS, DP, SB, SV, and IC contribu-
ted substantially to the conception and design of this study.
NW, CH, PN, PT, and IC contributed substantially to the
acquisition of data. PS and SB analyzed and interpreted the
data. PS, HS, and IC drafted the manuscript. DP, SB, SV, NW,
CH, PM, PT, and IC contributed substantially to its critical
revision. All the authors approved the final version submitted
for publication and take responsibility for the statements made
in the published article.
Acknowledgment. We would like to thank all the medical
staff members of the Faculty of Medicine Chiang Mai Univer-
sity in particular Malisa Poungsombat, Varunee Khamsan, and
Aumnart Mawoot for their assistance on data collection, and
all the physicians both government and private hospitals in
Chiang Mai Province, for their collaboration. We also wish to
thank the Bureau of Registration Administration, Ministry of
Interior for providing death certificate data for cancer registry.
This study was supported by research funding from Faculty
of Medicine, Chiang Mai University. The data sets used and/
or analyzed during the current study are available from the
corresponding author on reasonable request.
Conflict of interest statement. The authors have completed
and submitted the ICMJE Uniform Disclosure Form for Poten-
tial Conflicts of Interest. None of the authors disclose any con-
flict of interest.
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... 16 There are a number of studies from Thailand, which examined breast cancer biomarker profiles in various regions (Table 6). 10,[18][19][20][21][22][23][24][25] Similar to the index study conducted by Koonmee et al, 10 the majority of the Thai studies showed a rather low ER+ and higher than expected triple-negative breast cancer rates among Thai women. The range of ER+ cancers was as low as 50%, and the triplenegative rate ranged from 13% to 23%. ...
... The previous study has shown that patients with the HER2-enriched subtype will benefit the most from certain therapeutic regimens, such as dual HER2 blockade. 30 As expected, luminal tumors were the most common breast cancer subtypes in this study, which is similar to other Thai studies 10,15,21,23 and the global literature. 31 Luminal B was found to be the most frequent breast cancer subtype in KKU both pre-and post Pathum Raksa, while luminal A cancers were the most common subtype in Udonthani. ...
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