NO excess risk of breast cancer among female users of systemic glucocorticoids.

Recently published evidence suggests that hyperinsulinemia, insulin-like growth factors, and abnormal glucose intolerance may promote mammary carcinogenesis (1-6) and that women with type 2 diabetes are at increased risk for postmenopausal breast cancer (1, 3). Insulin and insulin-like growth factors are major determinants of proliferation and apoptosis (5, 6). Steroid hormones are also important in the etiology of breast cancer: both estrogens and androgens are dominant hormones in breast cancer development (7). Glucocorticoids are immunosuppressive steroid hormones widely used in the treatment of allergic and autoimmune diseases. Metabolic changes, including decreased glucose tolerance, are well-known side effects of glucocorticoids (8). Because these drugs are commonly used and breast cancer is fairly common, any relation between the two would have major public health implications. Therefore, we examined the risk of breast cancer in a large cohort of female glucocorticoids users.