Occupational exposures increase cancer risks. The Windsor Regional Cancer Centre in Windsor, Ontario, was the first Canadian cancer treatment center to collect the work histories of its patients, which were recorded using a computer-based questionnaire. Breast cancer cases represented the largest respondent group. The lifetime occupational histories of 299 women with newly diagnosed breast cancers were compared with those of 237 women with other cancers. Odds ratios (ORs) were calculated using logistic regression, adjusting for age, social class, and education. The OR for women £ 55 years of age with breast cancer who had ever farmed, compared with women of the same age with other cancers, was 9.05 (95% CI 1.06, 77.43). Patients’ occupational histories can help to inform understanding of cancer etiology and prevention. This effort points to a need for investigation of the possible association between breast cancer and agricultural hazards such as pesticides
