Cancer and work in Canada with particular reference to occupational risk factors in breast cancer patients in one community and related selected research methods used to investigate those factors

Abstract

Cancer represents a major cause of human morbidity and mortality. There is no scientific consensus regarding cancer causality or prevention. Occupational exposure potentially remains a major contributor to the incidence of this group of diseases, but the data to assess its impact continues to elude researchers and public health advocates. Among women in industrialised countries, breast cancer is the most prevalent cancer. The known or suspected risk factors, including family history and lifetime oestrogen load, can account for less than 50 percent of the cases. New hypotheses about the role of xenoestrogens and endocrine disrupting compounds are challenging the previous scientific precepts regarding cancer causality. Within this context, the extent to which a community-based occupational history data collection initiative can contribute to advancing our scientific understanding of associations between cancer and work is explored. The possibility that occupational histories data can find associations missed in conventional breast cancer research that ignore occupation is also explored. More specifically, the extent to which data derived from an occupational history questionnaire can provide insight into the potential association between breast cancer risk and farming is examined. Occupational histories of cancer patients contain data that could help to elucidate and inform our understanding of cancer aetiology and prevention. In the community of Windsor, Ontario, Canada a local cancer treatment centre responded to community concerns by cooperating in a collaborative research project to collect the occupational histories of cancer patients. 'Computerised Record of Occupation Made Easy' (CROME) was an innovative method that allowed individual patients to document their lifetime work histories. This data collection process represented the first time a local Canadian cancer treatment center had undertaken such an initiative. Based on the hypothesis generated by CROME, a new research study was launched - Lifetime Occupational History Record (LOHR). Over a two-and-a-half year period, all female patients at the Windsor Regional Cancer Centre with new incident breast cancer were invited to participate in a population-based case-control study along with an equivalent number of randomly selected community controls. A comprehensive lifetime history questionnaire was administered to subjects by interview. Data gathered included known or suspected risk factors along with a complete occupational history of all jobs ever worked. An occupational history of farming alone produced an Odds Ratio (OR) = 2.8 (Cl, 95%, 1.6-4.8). These findings are important for our understanding of cancer causality with implications for resolving the current scientific conflict regarding the role of occupationally caused carcinogenesis. Such collaborative, community-based studies also demonstrate the importance of community participation in the scientific research process.