Canadian census mortality and cancer cohort: A linked cohort for the surveillance of occupational exposure and cancer

Transcription

1 Canadian census mortality and cancer cohort: A linked cohort for the surveillance of occupational exposure and cancer Jill Hardt Occupational Cancer Research Centre Cancer Care Ontario November 5, CRDCN National Conference

2 Occupational cancer surveillance To systematically identify and monitor trends in the occurrence and distribution of work related cancers. Challenges: No clinical and pathological differences to detect work related cancers. Great cancer data, but where did they work? Cancers can occur years after a relevant carcinogenic exposure.

3 Data linkage 1991 Canadian Census 2B (long form) Age Province Education Income # of children Other socio demographic information Occupation and industry Canadian Mortality Database (CMDB) Date of death Tax Summary Files (TSF) Date of emigration/loss to follow up Canadian Cancer Registry Diagnosis (ICD 9, ICD O) Date of diagnosis

4 Derivation of the working cohort

5 Objectives 1. Hypothesis testing of suspected or known carcinogens and specific cancer sites using job exposure matrices 2. Targeted analyses of: Occupation/industry groups with known or suspected increased risk Understudied populations or cancer sites 3. Comprehensive analysis of cancer risks across occupation/industry groups

6 Methods Exposure assessment: Employment in the week prior to census day (June 4, 1991) or longest held job in previous year. Occupation: Standard Occupational Classification 1991 (SOC 91) Industry: Standard Industrial Classification 1980 (SIC 80) Disease assessment: Incident cancers diagnosed from January 1, 1992 to December 31, International Classification of Diseases (ICD 9) International Classification of Diseases for Oncology (ICD O 3)

7 Methods: Statistical Analysis Person years at risk: Start of follow up: Census day (June 4, 1991) End of follow up: date of cancer diagnosis (cancer registry), or date of death (mortality data), or date of emigration or loss to follow up (tax files), or end of cancer follow up (Dec 31, 2010), whichever occurred first Frequency: any cancer and 28 cancer types by industry and occupation Disease free survival analysis: Cox proportional hazards models Co variates: age at entry, region, education, income, parity

8 Results follow up: 1.1 million male workers: 122,900 cases 940,000 female workers: 86,000 cases Confirmed known work cancer associations: Mesothelioma among asbestos exposed workers Occupation group Hazard Ratio (95% CI) Construction workers 1.58 ( ) Machinery assemblers 2.23 ( ) and operators Plumbers 5.34 ( )

9 Results: Hypothesis testing Risk of selected cancers among wood dust exposed workers, Hazard Ratio (95% Confidence Interval) * Male workers only; Adjusted for age group, region and education level

10 Results: Targeted Analyses * Male workers only; Adjusted for age group, region and education level

11 Results: Comprehensive Analysis Occupation Cancer risk Risk Factors* Female office workers Breast Fewer children Hairdressers Bladder, Liver Hair dye, alcohol Food & beverage industry Oral, Lung, Esophagus Alcohol, smoking Agriculture Lip Sun at work Construction Stomach, Lung, Silica, cement, asbestos Mesothelioma Plastics manufacturing Mesothelioma Asbestos containing plastic products Agriculture Prostate cancer Pesticides Drivers Any cancer Diesel exhaust Health care Testis Shift work Finance & business, Any cancer Sedentary work,smoking Government Oil & gas industry Brain Oil, benzene Logging & forestry Nasal Wood dust *Bold indicates suspected work specific exposure

12 Strengths Large sample Able to explore rarer cancers and small occupation groups Reliably captures all incident cancer cases in Canada 18+ years of follow up Important given long latency of cancer Large distribution of ages at cohort entry

13 Limitations Exposure assessment: One time (Census day) Exposure duration? Job title only Healthy worker effect Confounders: Smoking? Alcohol? Personal protective equipment?

14 Conclusions Efficient approach for occupational cancer surveillance Nationally representative cohort Detected expected associations Useful for hypothesis testing, targeted analyses and exploratory analyses

15 Acknowledgments Health Analysis Division, Statistics Canada Occupational Cancer Research Centre Dr. Paul A. Demers Dr. M. Anne Harris Manisha Pahwa Joanne Kim Linda Kachuri Dr. Victoria Arrandale Trevor van Ingen Eliane Kim Lua Eiriksson Marcella Jones Anam Khan Funded by Ontario s Workplace Safety & Insurance Board (#11024) This research was supported by funds to the Canadian Research Data Centre Network (CRDCN) from the Social Science and Humanities research Council (SSHRC), the Canadian Institute for Health Research (CIHR), the Canadian Foundation for Innovation (CFI) and Statistics Canada. Although the research and analysis are based on data from Statistics Canada, the opinions expressed do not represent the views of Statistics Canada or the Canadian Research Data Centre Network (CRDCN).

16 Occupational Cancer Research Centre (OCRC) Cancer Care Ontario 525 University Avenue, 3rd Floor Toronto, ON M5G 2L3