Hormone alterations in breast cancer: Examining the hypotheses

Many of the epidemiologic risk factors for breast cancer offer clinicians l ittle help in anticipating who is likely to be struck with the disease or h ow to prevent it. There are only a handful of clinically significant risk f actors for breast cancer. These include being a woman, growing older, alrea dy having breast cancer in 1 breast, and having a first-degree relative (mo ther, sister, or daughter) who has been diagnosed with breast cancer. Most risk factors have a weak association with breast cancer, occur too infreque ntly, or are physiologic events not amenable to intervention. In recent yea rs, the search for breast cancer causes has fed to the identification of ge netic markers that seem to predispose some women to breast cancer. For deca des, however, researchers have been assessing and analyzing hormonal change s in the hope of finding a predictable breast cancer marker or cause that c an easily be manipulated to prevent or more effectively treat the disease. Nearly a dozen hormonal hypotheses of breast cancer causes have been propos ed -- among them estrogen excess, low luteal-phase progestational activity, adrenal androgen deficiency, ovarian androgen excess, melatonin deficiency , prolactin excess, and thyroid insufficiency. For most, the data are equiv ocal and inconclusive. The androgen deficiency hypotheses, however, may hav e some bearing on premenopausal breast cancer, and the ovarian dysfunction hypothesis may have some bearing on postmenopausal breast cancer.