Identification of occupational cancer risks in British Columbia - A population-based case-control study of 995 incident breast cancer cases by menopausal status, controlling for confounding factors

Lifetime occupational histories as well as information on known and suspect ed breast cancer risk factors were collected by means of a self-administere d questionnaire from 1018 women with incident breast cancer ascertained fro m the British Columbia Cancer Registry, and from 1020 population controls. A matched case-control study design was used. Conditional logistic regressi on for matched sets data and the likelihood ratio were used in a two-step p rocedure and were performed separately for pre-menopausal women, post-menop ausal women, and for all cases combined. Excess risk was noted for several white-collar occupations. Significantly increased risk was observed: (1) am ong pre-menopausal women: in electronic dataprocessing operators; barbers a nd hairdressers; in sales and material processing occupations; and in the f ood, clothing, chemical and transportation industries; (2) among post-menop ausal women: in schoolteaching; in medicine?, health, and nursing occupatio ns; in Laundry and dry-cleaning occupations; and in the aircraft and automo tive, including gasoline service station, industries, Several significant a ssociations were also seen in the combined group of pre- and post-menopausa l women, particularly in crop farmers and in the fruit and vegetable, publi shing and printing; and motor vehicle repair industries. The results of thi s study suggest excess breast cancer risk in a number of occupations and in dustries, notably those that entail exposure to solvents and pesticides.