Variation in female breast cancer risk by occupation.

Data from a population-based case control study were used to estimate occupation-specific relative risks for female breast cancer, adjusted for established breast cancer risk factors. Breast cancer cases under age 75 were identified from tumor registries in four states. Controls were randomly selected from driver's license and Medicare beneficiary lists. Information on usual occupation and risk factors was obtained by telephone interview. Odds ratios from logistic regression adjusted for age, state, body mass index, benign breast disease, family history of breast cancer, menopausal status, age at menarche, parity, age of first birth, lactation history, education, and alcohol consumption were calculated for each of 26 occupational groups. Complete occupational information was obtained for 6,835 cases and 9,453 controls. Of 26 occupational groups, only "administrative support occupations" had a statistically significantly increased risk of breast cancer (OR = 1.15, 95% CI 1.06-1.24). In these data, no specific occupational group had an unusual risk of breast cancer. Increased risks reported elsewhere for nurses and teachers were not corroborated.