A case-control study of breast cancer and psychotropic drug use.

The relative risk of breast cancer incidence and tumor promotion associated with psychotropic drug consumption was evaluated in 151 patients with newly diagnosed neoplasms and 151 hospital controls. No significantly altered risk of breast cancer was found in association with the use of diazepam, chlordiazepoxide, antidepressants, major tranquillizers, sedatives or hypnotics, even after adjustment for known menstrual and reproductive risk factors. No substantial evidence of tumor promotion effects was found, as measured by altered age-at-onset of disease or altered clinical stage at presentation. Psychotropic drug use was inversely related to subject ponderosity (measured by the Quetelet Index) and while this did not confound risk estimates, it may be important in exploring biologic hypotheses of psychotropic drug use and breast cancer.