Lawrence Paszat

Institute for Clinical Evaluative Sciences, Toronto, Ontario, Canada

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Publications (191)1219.28 Total impact

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    ABSTRACT: Background: A clinical risk index employing age, sex, family history of colorectal cancer (CRC), smoking history and body mass index (BMI) may be useful for prioritizing screening with colonoscopy. The aim of this study was to conduct an external evaluation of a previously published risk index for advanced neoplasia (AN) in a large, well-characterized cohort. Methods: Five thousand one hundred thirty-seven asymptomatic persons aged 50 to 74 (54.9 % women) with a mean age (SD) of 58.3 (6.2) years were recruited for the study from a teaching hospital and colorectal cancer screening centre between 2003 and 2011. All participants underwent a complete screening colonoscopy and removal of all polyps. AN was defined as cancer or a tubular adenoma, traditional serrated adenoma (TSA), or sessile serrated adenoma (SSA) with villous characteristics (≥25% villous component), and/or high-grade dysplasia and/or diameter ≥10 mm. Risk scores for each participant were summed to derive an overall score (0-8). The c-statistic was used to measure discriminating ability of the risk index. Results: The prevalence of AN in the study cohort was 6.8 %. The likelihood of detecting AN increased from 3.6 to 13.1 % for those with a risk score of 1 to 6 respectively. The c-statistic for the multivariable logistic model in our cohort was 0.64 (95 % CI = 0.61-067) indicating modest overlap between risk scores. Conclusions: The risk index for AN using age, sex, family history, smoking history and BMI was found to be of limited discriminating ability upon external validation. The index requires further refinement to better predict AN in average risk persons of screening age.
    Full-text · Article · Dec 2015 · BMC Gastroenterology
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    ABSTRACT: Timely follow-up of fecal occult blood screening with colonoscopy is essential for achieving colorectal cancer mortality reduction. This study evaluates the effectiveness of two ongoing interventions designed to improve colonoscopy uptake after a positive fecal occult blood test (FOBT) result within Ontario's population-wide ColonCancerCheck program. The first was a revision of mailed FOBT lab results to physicians to explicitly define a positive FOBT and to recommend colonoscopy. The second was a letter to participants informing them of the positive FOBT and urging them to seek appropriate follow-up. Prospective cohort study using Ontario's ColonCancerCheck program data sets (2008-2011), linked to provincial administrative health databases. Crude rate ratios were calculated to assess determinants of colonoscopy uptake among an Ontario-wide FOBT-positive cohort with rolling enrolment, followed from October 2008 through February 2011. Segmented time-series regression was used to assess the average additional change in colonoscopy uptake after FOBT-positive status following the introduction of two ongoing interventions among the same cohort. A notification mailed directly to FOBT-positive screening participants was observed to increase colonoscopy uptake, beyond the modest average underlying increase throughout the study period, by an average of 3% per month (multivariable-adjusted RR: 1.03, 95% CI: 1.00-1.06). However, revision of the existing FOBT result notification to physicians was observed to have no effect. Direct participant notification of a positive FOBT result improved adherence with follow-up colonoscopy in Ontario's population-wide ColonCancerCheck program. Further participant-directed interventions may be an effective means of maximizing adherence in population-wide screening.
    Full-text · Article · Dec 2015 · Implementation Science
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    ABSTRACT: Background: Screening for cervical, breast and colon cancers, and elevations of cholesterol and glucose, reduces premature cause-specific mortality from these cancers and circulatory diseases. Despite primary care reforms and incentives, and promotion of cancer-screening programs among individuals, participation is suboptimal. We aimed to examine participation as of Dec. 31, 2011, by factors of deprivation, demographics and primary care at the small-area level. Methods: From health care administrative databases, we identified people eligible for each screening test, and their participation, in each dissemination area (referred to as small areas, n = 18 950) in Ontario. We calculated rates for each test among small areas (overall and stratified by demographic, socioeconomic and primary care descriptors) and stratified by sex for all tests combined. We loaded all data into a geographic information system. Funnel plots were generated showing the percentage of eligible people who completed screening for all tests by small area, stratified by sex. Overall and stratified screening prevalence ratios were calculated among small areas. Results: Among small areas, the mean and SD for participation in all tests combined was 31.6% (SD 11.0%) for women and 41.2% (SD 12.0%) for men. Screening prevalence among small areas, for each test and for all tests combined, overall and stratified by sex, declined with decreasing percentage with high school completion, decreasing socioeconomic quintile, and decreasing percentage with an identifiable primary care physician. Interpretation: Our results show that the rate of participation in all eligible screening tests among small areas is much lower than the rate of participation in any one particular test. This finding has implications for the design and implementation of strategies to improve rates of screening.
    Full-text · Article · Oct 2015
  • R Sutradhar · S Gu · R H Glazier · L F Paszat
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    ABSTRACT: Objective: To determine whether visits to a primary care provider (PCP) are associated with the uptake of periodic mammograms as women get older. Methods: The cohort consisted of 2,389,889 women resident in Ontario, Canada, aged 50 to 79 at any point from 2001 to 2010, who were cancer-free and eligible for the Ontario Health Insurance Plan prior to study entry. Non-parametric estimation was used to describe the mean cumulative number of periodic mammograms for women with and without recent exposure to a PCP, as a function of age. Using age as the time scale, a recurrent event regression model was also implemented to examine the association between exposure to a PCP and rate of periodic mammograms, adjusted for income quintile and comorbidity. Results: The mean observation window was 7.0 years. Uptake of periodic mammograms was significantly higher for women with recent exposure to a PCP compared with those without. This trend remained consistent as women aged, and the magnitude of the association increased for women aged 65 or older. The relative rate of periodic mammograms was lower than 1 and consistently decreased as women from lower income quintiles were compared with women from the wealthiest quintile. Conclusion: Visits to a PCP play an important role in uptake of periodic mammograms, and this association increases as women age.
    No preview · Article · Sep 2015 · Journal of Medical Screening
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    ABSTRACT: Survivors of young adult malignancies are at risk of accumulated exposures to radiation from repetitive diagnostic imaging. We designed a population-based cohort study to describe patterns of diagnostic imaging and cumulative diagnostic radiation exposure among survivors of young adult cancer during a survivorship time period where surveillance imaging is not typically warranted. Young adults aged 20-44 diagnosed with invasive malignancy in Ontario from 1992-1999 who lived at least 5 years from diagnosis were identified using the Ontario Cancer Registry and matched 5 to 1 to randomly selected cancer-free persons. We determined receipt of 5 modalities of diagnostic imaging and associated radiation dose received by survivors and controls from years 5-15 after diagnosis or matched referent date through administrative data. Matched pairs were censored six months prior to evidence of recurrence. 20,911 survivors and 104,524 controls had a median of 13.5 years observation. Survivors received all modalities of diagnostic imaging at significantly higher rates than controls. Survivors received CT at a 3.49-fold higher rate (95 % Confidence Interval [CI]:3.37, 3.62) than controls in years 5 to 15 after diagnosis. Survivors received a mean radiation dose of 26 miliSieverts solely from diagnostic imaging in the same time period, a 4.57-fold higher dose than matched controls (95 % CI: 4.39, 4.81). Long-term survivors of young adult cancer have a markedly higher rate of diagnostic imaging over time than matched controls, imaging associated with substantial radiation exposure, during a time period when surveillance is not routinely recommended.
    Full-text · Article · Sep 2015 · BMC Cancer

  • No preview · Article · Aug 2015
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    ABSTRACT: There are limited data on health care use among survivors of young adult cancers. We aimed to describe patterns of hospitalization among a cohort of long-term survivors compared with noncancer controls. Persons diagnosed between the ages of 20 and 44 years with malignancies in Ontario, Canada, from 1992 to 1999, who lived at least 5 years recurrence free, were identified using the Ontario Cancer Registry and matched to noncancer controls. Hospitalizations were determined using hospital discharges, and rates were compared between survivors and controls. The absolute excess rate of hospitalizations was determined for each type of malignancy in survivors per 100 person-years of follow-up. The cohort included 20,275 survivors and 101,344 noncancer controls. During the study period, 6,948 (34.3%) survivors were admitted to the hospital and the adjusted relative rate (ARR) of hospitalizations in survivors compared with controls was 1.51 (95% CI, 1.48 to 1.54). The rate of hospitalization was highest for survivors of upper GI, leukemia, and urologic malignancies. The hospitalization rate (per person) for survivors significantly decreased from 0.22 in the first time period examined (5 to 8 years after diagnosis) to 0.15 in the last time period examined (18 to 20 years after diagnosis, P < .0001). However, at all time periods, survivors were more likely to be hospitalized than controls (ARR at 5 to 8 years, 1.67 [95% CI, 1.57 to 1.81]; ARR at 18 to 20 years, 1.22 [95% CI, 1.08 to 1.37]). Survivors of young adult cancers have an increased rate of hospitalization compared with controls. The rate of hospitalization for 20-year survivors did not return to baseline, indicating a substantial and persistent burden of late effects among this generally young population. © 2015 by American Society of Clinical Oncology.
    Preview · Article · Jul 2015 · Journal of Clinical Oncology
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    ABSTRACT: Mastectomy is effective treatment for ductal carcinoma in situ (DCIS) but some women will develop chest wall recurrence. Most chest wall recurrences that develop after mastectomy are invasive cancer and are associated with poorer prognosis. Past studies have been unable to identify factors predictive of chest wall recurrence. Therefore, it remains unclear if a subset exists of women with DCIS treated by mastectomy experience a high rate of recurrence in whom more aggressive treatment may be of benefit. We report outcomes of all women in Ontario (N = 1,546) diagnosed with pure DCIS from 1994 to 2003 treated with mastectomy without radiotherapy and evaluate factors associated with the development of chest wall recurrence. Treatments and outcomes were validated by chart review. Proportional differences were compared using Chi square analyses. Survival analyses were used to study the development of chest wall recurrence in relation to patient and tumor characteristics. Median follow-up was 10.1 years. Median age was 57.1 years. 36 patients (2.3%) developed chest wall recurrence. The 10-year actuarial chest wall recurrence-free survival rates and invasive chest wall recurrence-free survival rates were 97.6 and 98.6%, respectively. There was no difference in cumulative 10 year rates of chest wall recurrence by age at diagnosis (<40 years = 5.2%, 40–44 years = 1.3%, 45–50 years = 2.9%, >50 years = 2.1%; p = 0.19), nuclear grade (high = 3.0%, intermediate = 1.4%, low = 1.0%, unreported = 2.5%; p = 0.41), or among women with close or positive resection margins (positive = 3.0%, 2 mm or less = 1.4%, >2 mm = 1.5%, unreported = 2.8%; p = 0.51). On univariate and multivariable analysis, none of the factors were significantly associated with the development of chest wall recurrence. In this population cohort, individuals treated by mastectomy experienced low rates of chest wall recurrence. We did not identify a subset of patients with a high rate of chest wall recurrence, including those with positive margins.
    Preview · Article · Jul 2015 · SpringerPlus
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    ABSTRACT: Validated biomarkers are needed to improve risk assessment and treatment decision-making for women with ductal carcinoma in situ (DCIS) of the breast. The Oncotype DX® DCIS Score (DS) was shown to predict the risk of local recurrence (LR) in individuals with low-risk DCIS treated by breast-conserving surgery (BCS) alone. Our objective was to confirm these results in a larger population-based cohort of individuals. We used an established population-based cohort of individuals diagnosed with DCIS treated with BCS alone from 1994 to 2003 with validation of treatment and outcomes. Central pathology assessment excluded cases with invasive cancer, DCIS < 2 mm or positive margins. Cox model was used to determine the relationship between independent covariates, the DS (hazard ratio (HR)/50 Cp units (U)) and LR. Tumor blocks were collected for 828 patients. Final evaluable population includes 718 cases, of whom 571 had negative margins. Median follow-up was 9.6 years. 100 cases developed LR following BCS alone (DCIS, N = 44; invasive, N = 57). In the primary pre-specified analysis, the DS was associated with any LR (DCIS or invasive) in ER+ patients (HR 2.26; P < 0.001) and in all patients regardless of ER status (HR 2.15; P < 0.001). DCIS Score provided independent information on LR risk beyond clinical and pathologic variables including size, age, grade, necrosis, multifocality, and subtype (adjusted HR 1.68; P = 0.02). DCIS was associated with invasive LR (HR 1.78; P = 0.04) and DCIS LR (HR 2.43; P = 0.005). The DCIS Score independently predicts and quantifies individualized recurrence risk in a population of patients with pure DCIS treated by BCS alone. Electronic supplementary material The online version of this article (doi:10.1007/s10549-015-3464-6) contains supplementary material, which is available to authorized users.
    Full-text · Article · Jun 2015 · Breast Cancer Research and Treatment
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    ABSTRACT: Background: Data suggest the overuse of repeat colonoscopies, especially in patients at low risk for colorectal cancer. Our objective was to evaluate the time to repeat colonoscopies in low-risk patients aged 50-79 years old and the associated patient- and endoscopist-related factors. Methods: All patients aged 50-79 years of age who underwent a complete outpatient colonoscopy with a negative result between 2000 and 2007 were identified from the Ontario Health Insurance Plan database. A colonoscopy performed within 5.5 years of follow-up after the index colonoscopy was considered an early repeat colonoscopy. Patient, endoscopist and endoscopy setting characteristics were recorded and their association with an early repeat colonoscopy was determined using an extended Cox proportional hazards regression model. Results: The cohort consisted of 546 467 patients: 55.4% of the patients were female with a mean age of 61.1 years (95% confidence interval [CI] 61.1-61.2). The cumulative percentage of early repeat colonoscopy after 5.5 years was 33.7%. The rate decreased significantly between 2000 and 2007 (hazard ratio [HR] 0.35, 95% CI 0.34-0.36). General surgeons were associated with a higher risk of early repeat colonoscopy than gastroenterologists (HR 1.27, 95% CI 1.25-1.28). Endoscopists practising in a nonhospital setting were more likely to perform an early repeat colonoscopy (HR 1.26, 95% CI 1.22-1.30) than endoscopists at a hospital. Interpretation: This study showed that there was overuse of early repeat colonoscopy in more than 30% of patients who were at low risk for colorectal cancer. The risk decreased significantly between 2000 and 2007 but was still greater than 20% in 2007. Our findings can be used to develop targeted educational interventions among subgroups of endoscopists with a higher rate of early repeat colonoscopy.
    Full-text · Article · Jun 2015
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    Ilia Makedonov · Sumei Gu · Lawrence F Paszat
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    ABSTRACT: The Ontario Breast Screening Program (OBSP) is a population-based breast screening programme, not requiring physician referral. OBSP invites women by mail to book their next screens. However, women who do not participate in the OBSP, may be referred by physicians to non-OBSP mammography facilities, which do not remind women to book their next screen. We identified women without breast cancer prior to June 30, 2011, having bilateral mammography (M) during a baseline period at age 50 - 69 at OBSP or non-OBSP facilities, and during a re-exposure period, at the same facility type. We used a case-control design to study the association of facility type and having M during an outcome period. Cases were women failing to receive the outcome M. Controls were matched by age, census tract, and socioeconomic status. Exposure was baseline facility type. Covariates were comorbidity, residential mobility, and primary care physician (PCP) characteristics. Conditional logistic regression analysis was performed. Cases were less likely to have been screened at OBSP facilities. Failure to receive the outcome M was associated with having moved after re-exposure M (OR = 1.61, 95% confidence interval (CI) 1.52, 1.71), having a male PCP (OR = 1.05, 95% CI 1.02, 1.05), or a higher Charlson score (OR = 1.06 per unit increase, 95% CI 1.03, 1.09). Having re-exposure M at an OBSP facility (OR = 0.18, 95% CI 0.18, 0.19)., having a Canadian trained PCP (OR = 0.83, 95% CI 0. 8, 0.87), and having a PCP one year after the re-exposure M (OR = 0.81, 95% CI 0.68, 0.97) were protective against failure to receive the outcome M. The OBSP, not requiring physician referral, and inviting women by mail to book their next screen, is associated with a lower probability of failure to reattend for subsequent screening than screening by PCP referral to non-OBSP facilities.
    Preview · Article · Apr 2015 · BMC Cancer
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    ABSTRACT: Colon Cancer Check (CCC), Ontario's organized colorectal cancer (CRC) screening program, uses guaiac fecal occult blood testing (gFOBT). To reduce CRC-related mortality, persons with a positive gFOBT must have colonoscopy. We identified factors associated with failure to have colonoscopy within 6 months of a positive gFOBT. Population-based, retrospective cohort analysis of CCC participants with positive gFOBT (April 2008 to December 2009) using health administrative data. Patient, physician and health care utilization factors associated with a lack of follow-up colonoscopy were identified using descriptive and multivariate analyses. There were 21,839 participants with a positive gFOBT; 14,091 (64%) had colonoscopy within 6 months. The strongest factors associated with failure to follow-up were recent colonoscopy (in 2 years prior vs. >10 years or never, OR: 4.31, 95% C.I.: 3.82, 4.86), as well as repeat gFOBT (OR: 6.08, 95% C.I.: 5.46, 6.78) and hospital admission (OR: 4.35, 95% C.I.: 3.57, 5.26) in the follow-up period. In the first 18 months of the CCC Program, 1/3 of those with a positive gFOBT did not have colonoscopy within 6 months. Identification of potentially modifiable factors associated with failure to follow up lay the groundwork for interventions to address this critical quality gap. Copyright © 2015. Published by Elsevier Inc.
    No preview · Article · Apr 2015 · Preventive Medicine

  • No preview · Article · Apr 2015 · Gastroenterology
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    Full-text · Article · Apr 2015 · Gastroenterology
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    ABSTRACT: Women with diabetes have higher breast cancer incidence and mortality. The purpose of this study was to examine the impact of diabetes on stage at breast cancer diagnosis, as a possible reason for their higher mortality. Using population-based health databases from Ontario, Canada, this retrospective cohort study examined stage at diagnosis (II, III, or IV vs I) among women aged 20-105 years who were newly diagnosed with invasive breast cancer between 2007 and 2012. We compared those with diabetes to those without diabetes. Diabetes was defined based on medical records using a validated algorithm. Among 38,407 women with breast cancer, 6115 (15.9 %) women had diabetes. Breast cancer patients with diabetes were significantly more likely to present with advanced-stage breast cancer than those without diabetes. After adjustment for mammograms and other covariates, diabetes was associated with a significantly increased risk of Stage II [adjusted odds ratio (aOR) 1.14, 95 % confidence interval (CI) 1.07, 1.22], Stage III (aOR 1.21, 95 % CI 1.11, 1.33), and Stage IV (aOR 1.16, 95 % CI 1.01, 1.33) versus Stage I breast cancer. Women with diabetes had a higher risk of lymph node metastases (aOR 1.16, 95 % CI 1.06, 1.27) and tumors with size over 2 cm (aOR 1.16, 95 % CI 1.06, 1.28). Diabetes was associated with more advanced-stage breast cancer, even after accounting for differences in screening mammogram use and other factors. Our findings suggest that diabetes may predispose to more aggressive breast cancer, which may be a contributor to their higher cancer mortality.
    No preview · Article · Mar 2015 · Breast Cancer Research and Treatment
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    ABSTRACT: A clinical risk index that uses distal colorectal findings at flexible sigmoidoscopy (FS) in conjunction with easily determined risk factors for advanced proximal neoplasia (APN) may be useful for tailoring or prioritizing screening with colonoscopy. To conduct an external evaluation of a previously published risk index in a large, well-characterized cohort. Cross-sectional. Teaching hospital and colorectal cancer screening center. A total of 5139 asymptomatic persons aged 50 to 74 (54.9% women) with a mean age (± SD) of 58.3 (± 6.2) years. Between 2003 and 2011, all participants underwent a complete screening colonoscopy and removal of all polyps. Participants were classified as low, intermediate, or high risk for APN, based on their composite risk index scores. The concordance or c-statistic was used to measure discriminating ability of the risk index. A total of 167 persons (3.2%) had APN. The prevalence of those with APN among low-, intermediate-, and high-risk categories was 2.1%, 2.9%, and 6.5%, respectively. High-risk individuals were 3.2 times more likely to have APN compared with those in the low-risk category. The index did not discriminate well between those in the low- and intermediate-risk categories. The c-statistic for the overall index was 0.62 (95% confidence interval, 0.58-0.66). Distal colorectal findings were derived from colonoscopies and not FS itself. The risk index discriminated between those at low risk and those at high risk, but it had limited ability to discriminate between low- and intermediate-risk categories for prevalent APN. Information on other risk factors may be needed to tailor, or prioritize, access to screening colonoscopy. Copyright © 2015 American Society for Gastrointestinal Endoscopy. Published by Elsevier Inc. All rights reserved.
    No preview · Article · Mar 2015 · Gastrointestinal Endoscopy
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    ABSTRACT: The potential for cancers to not be detected on colonoscopy is increasingly recognised, but little is known about patient outcomes. The objective of this study was to assess the outcomes of patients diagnosed with postcolonoscopy colorectal cancers (PCCRCs). We conducted a population-based retrospective cohort study, including all patients diagnosed with colorectal cancer (CRC) in Ontario, Canada from 2003 to 2009. Patients were categorised into three groups: DETECTED (diagnosed within 6 months of first colonoscopy), PCCRC (diagnosed 6-36 months after first colonoscopy) or NOSCOPE (no colonoscopy within 36 months of diagnosis). Univariate and multivariable analyses were conducted to study overall survival, surgical treatment, emergency presentation and surgical complications. Overall, 45 104 patients were included, with 2804 being classified as having a PCCRC. Compared with the DETECTED group, PCCRC was associated with a significantly higher likelihood of stage IV disease (17.2% vs 12.9%), worse overall survival (5 year OS: 60.8% vs 68.3%, p<0.0001; adjusted HR: 1.25, 95% CI 1.17 to 1.32, p<0.0001), a higher likelihood of emergency presentation (OR: 2.86, 95% CI 2.56 to 3.13, p<0.001) and lower likelihood of surgical resection (OR: 0.61, 95% CI 0.55 to 0.67, p<0.001). However, patients with PCCRC had significantly better outcomes than those in the NOSCOPE group (stage IV: 37.1%, 5 year OS: 38.9%) CONCLUSIONS: Compared with CRC detected by colonoscopy, PCCRCs are associated with a higher risk of emergent presentation, a lower likelihood of surgical resection and most notably, significantly worse oncological outcomes. However, they have better outcomes than patients with no recent colonoscopy. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
    No preview · Article · Mar 2015 · Gut
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    ABSTRACT: 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.
    No preview · Article · Feb 2015 · International Journal of Cancer

  • No preview · Conference Paper · Feb 2015

  • No preview · Article · Dec 2014 · JAMA The Journal of the American Medical Association

Publication Stats

6k Citations
1,219.28 Total Impact Points

Institutions

  • 2002-2015
    • Institute for Clinical Evaluative Sciences
      Toronto, Ontario, Canada
  • 2000-2015
    • University of Toronto
      • • Institute of Health Policy, Management and Evaluation
      • • Department of Surgery
      • • Department of Radiation Oncology
      • • Institute for Clinical Evaluative Sciences
      • • Department of Medicine
      Toronto, Ontario, Canada
  • 2004-2014
    • Sunnybrook Health Sciences Centre
      • • Department of Radiation Oncology
      • • Division of Medical Oncology and Hematology
      Toronto, Ontario, Canada
  • 1998-2010
    • Queen's University
      • • Department of Community Health and Epidemiology
      • • Department of Oncology
      Kingston, Ontario, Canada
  • 2009
    • Harvard University
      Cambridge, Massachusetts, United States
  • 2007
    • University of Texas MD Anderson Cancer Center
      • Department of Gynecologic Oncology
      Houston, TX, United States
  • 2006
    • McMaster University
      • Department of Obstetrics and Gynaecology
      Hamilton, Ontario, Canada
  • 2003
    • Cancer Care Ontario
      Toronto, Ontario, Canada
  • 1997-2000
    • Kingston General Hospital
      Kingston, Ontario, Canada