A PROSPECTIVE-STUDY OF ENDOGENOUS HORMONES AND BREAST-CANCER

To examine the association prospectively between endogenous hormones a nd breast cancer. a population-based, nested case-control study was co nducted using serum collected in 1974. Serum hormone levels among 51 w omen, who subsequently developed breast cancer, were compared with con trols matched on age and time since last menstrual period. The levels of estrogens, progesterone, sex-hormone binding globulin, and androste nedione were compared between cases and controls. No statistically sig nificant differences in endogenous hormones levels were observed betwe en women who subsequently developed breast cancer and controls. Despit e the fact that risk factors for breast cancer implicate endogenous ho rmones, especially estrogen, in the etiology of this disease, our stud y failed to demonstrate a statistically significant association betwee n endogenous hormones and the risk of breast cancer. If there is an as sociation between endogenous hormones and breast cancer, the magnitude of the effect is weak.