Androgens and estrogens in the etiology and prevention of breast cancer.

Breast cancer is the most common cause of cancer death in women worldwide. Rates vary about fivefold around the world, but they are increasing in regions that until recently had low rates of disease. Despite the numerous uncertainties surrounding the etiology of breast cancer, intensive epidemiological, clinical, and genetic studies have identified a number of biologic and social traits as risk factors associated with breast cancer. Principal among them are the evidence of BRCA1 and BRCA2 susceptibility genes, familial history of breast cancer, age, higher socioeconomic status, ionizing radiation, tallness in adult life, alcohol consumption, and a variety of hormone and metabolic factors. Among the hormonal influences, a relevant etiological function has been ascribed to elevated levels of estrogens, their active metabolites, and androgens. These endocrine factors may represent future targets for breast cancer prevention.