Occupational Histories of Essex County Cancer Patients
| Principal investigator(s): | Kevin M. Gorey (University of Windsor) |
| Co-investigator(s): | James Brophy, Deborah Hellyer (Occupational Health Clinics for Ontario Workers); Margaret M. Keith (Windsor Occupational Health Information Service); Ethan Laukkanen (Windsor Regional Cancer Centre) |
| Sponsoring Institution: | University of Windsor |
Results
564 female breast cancer cases and 599 female controls were enrolled in the study. Their histories were compared using logistic regression statistical techniques. After controlling for traditional risk factors and other covariates, an occupational history of farming alone produced an odds ratio (OR) = 2.8 (CI, 95%, 1.6- 4.8). Women who were employed in agriculture and were subsequently employed in auto-related industries had an odds ratio (OR) = 4.1 (CI, 95%, 1.7 - 9.9) and in health care had an odds ratio (OR) = 2.3 (CI, 95%, 1.1 - 4.6).
Objective
Over the past 30 years, there has been an almost 1% annual increase of breast cancer incidence in Canada. The majority of breast cancer cases cannot be explained by known risk factors. Increasing evidence suggests that synthetic chemicals may be contributing to the incidence of this disease. Although such carcinogens exist in many workplace environments, few occupational breast cancer studies have been conducted in Canada. This lack of attention to the possible occupational associations with cancer contributes to the under-reporting and minimal recognition of occupational risk factors in the etiology of breast carcinogenesis. While laboratory-based research can identify isolated carcinogenic agents, population-based studies have the advantage of being able to evaluate interactive and cumulative effects in a real world environment. Such information can advance our understanding of cancer etiology in a practical manner and may ultimately facilitate the formulation of public health interventions. The specific objective of the study was to investigate whether women who have ever engaged in farming have an increased risk of breast cancer.
Methods
Over a two-and-a-half year period (2000-2002), all female patients at the Windsor Regional Cancer Centre with new incident breast cancer were invited to participate in a 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.
Conclusions
This study provides evidence of an association between farming and breast cancer risk, as well as an interactive effect between occupational farming exposures and subsequent exposures in other occupational environments. It might be extrapolated that exposure to pesticides or other farm exposures initiate the breast cancer process and subsequent exposures to agents in auto-related industry, health care or other industries act as promoters. This interactive effect requires further study and consideration. Moreover, we need a clearer understanding of the effects of farming exposures during the early periods of life when breast tissue is most vulnerable. This would fill a glaring gap in our occupational cancer knowledge base and aid our general understanding about the causes of breast cancer.
For more information:
jimbrophy@sympatico.ca
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