Hormones and breast cancer.

Patients with successfully managed breast cancer have generally been denied subsequent exposure to increased levels of estrogen (endogenous or exogenous) based on the belief that exacerbation of the cancer would occur. The advent of oral contraceptives, the trend toward childbearing later in life, and the demonstration of the protective value of menopausal estrogen replacement therapy against osteoporosis and cardiovascular disease requires that this issue be reexamined. New information bearing on this subject includes the recognition of estrogen receptors, the isolation of youth rather than pregnancy as the factor resulting in poor prognosis, epidemiologic studies showing no increased risk of breast cancer in women using oral contraceptives or taking hormonal replacement therapy, the beneficial effect of pregnancy subsequent to successfully managed breast cancer, and the absence of an adverse effect of oral contraceptives upon established breast cancer. In view of the lack of evidence relating estrogen to exacerbation of existing breast cancer, it may be in the best interest of our patients to liberalize our attitude to renewed hormonal exposure in patients with successfully managed breast cancer.