Breast cancer prevention by antiestrogens.
A new era has been entered with the first demonstration that an antiestrogen can prevent breast cancer. In a landmark study tamoxifen was shown to reduce the incidence of breast cancer by approximately 50%. The reduction was observed in pre- and postmenopausal women at increased risk of breast cancer. Invasive cancers were reduced, the reduction being in the estrogen receptor-positive cancers. No preventive effect was observed for estrogen receptor-negative tumors. In situ cancers were also significantly reduced. A collateral benefit was a significant reduction in fractures due to osteoporosis. Adverse effects included a very small increase in the incidence of endometrial cancer, cataracts, and stroke. The benefits appear to outweigh the risks for those at high risk. Preliminary studies of a new selective estrogen receptor modulator (SERM 2), raloxifene, developed for the prevention of osteoporosis, have shown that the breast cancer rate was reduced by more than 50% without any concomitant increase in endometrial cancer. The search for a SERM 3, and beyond, may lead to the development of drugs that have the beneficial effects of estrogen while preventing breast cancer and osteoporosis.
Osborne
M P
MP
Strang Cornell Breast Center, New York, New York 10021, USA. osborne@strang.org
D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000378:metabolism / Q000517:prevention & control*; D004965:Estrogen Antagonists / Q000627:therapeutic use*; D004967:Estrogens / Q000378:metabolism*; D005260:Female; D006801:Humans; D010024:Osteoporosis / Q000517:prevention & control; D013629:Tamoxifen / Q000627:therapeutic use*
D018931:Antineoplastic Agents, Hormonal; D004965:Estrogen Antagonists; D004967:Estrogens; D013629:Tamoxifen