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.
PIP: This review raises the issue whether endogenous or exogenous estrogens, such as those circulating during pregnancy, oral contraception or hormonal replacement therapy, have an adverse effect on the course of breast cancer. Breast cancer has traditionally been managed by terminating pregnancy and contraindicating estrogen therapy. Breast cancer is difficult to detect in pregnancy, even by mammography. It is now recognized that pregnant women without axillary lymph node cancer have a favorable prognosis, that most breast cancers arising during pregnancy are not estrogen-receptor positive, and that youth, not pregnancy, is the independent risk factor for poor prognosis. Women whose cancer was successfully managed often do better if they subsequently become pregnant than do those who do not. Furthermore, additive hormonal therapy, and therapy using tamoxifen, a estrogen- antagonist, are effective. The U.S. Food and Drug Administration stated in 1984 that there is no increased risk of breast cancer in users of oral contraceptives. Possibly the improved surveillance and earlier diagnosis of pill users, who see doctors regularly, contribute toward better prognosis of those who do develop cancer. So far there is no evidence that women on hormonal replacement therapy are at increased risk for breast cancer.