Although both prolactin and growth hormone are believed to play roles in the development and growth of rodent mammary cancer, the role of these hormones in human breast cancer is uncertain. Under carefully specified conditions, serum levels of these hormones were determined by radioimmunoassay (RIA) and prolactin was determined by bioassay in 18 premenopausal women with breast cancer, 23 healthy women with a strong family history of breast cancer, and 39 healthy women with no significant family history of breast cancer. Parity was associated strongly with decreased prolactin levels, and increasing age was associated strongly with decreased growth hormone levels. After controlling for these variables, no differences in prolactin or growth hormone levels were found among the three groups of women. These data do not support roles for these RIA-measured hormones or bioassay-measured prolactin in premenopausal or familial breast cancer in omnivorous white women. VSports手机版.