Women should consider all the scientific evidence available, consult with their physician, and then decide whether they should take a chemopreventive agent to lower their risk of breast cancer, according to scientists with the American Council on Science and Health (ACSH). A new booklet, Chemoprevention of Breast Cancer, has been written for ACSH by Kathleen Meister, M.S. The report is based on a paper prepared for ACSH by Scott Lippman, M.D., professor and chair of the Department of Clinical Cancer Prevention at the University of Texas-M.D.Anderson Cancer Center, with Powel Brown, M.D., Ph.D., and will soon be published in an academic medical journal.
The only such chemopreventive agents available now are tamoxifen and raloxifene. These drugs are selective estrogen receptor modifiers, or SERMs, and lower the risk of breast cancer, it is believed, by blocking the effect of estrogen on breast tissue. Tamoxifen has been used for over 20 years to make less likely the development of new lesions after the removal of a primary breast cancer. In 1998 it was approved for chemoprevention, which is the reduction of cancer risk before cancer has even been detected. Raloxifene was introduced for the prevention of osteoporosis in 1998 and for the treatment of osteoporosis in 1999, but it has not yet been approved for the chemoprevention of breast cancer. Preliminary studies have suggested that it may be as effective as tamoxifen, and might be safer, in this area. Tamoxifen can cause the proliferation of uterine cells and thus increases the risk of uterine cancer. Raloxifene does not have this side effect, but both drugs have adverse effects that have to be taken into account before they are prescribed. Ongoing studies may shed much more light on who should and should not take these drugs, and some of these results may become known next year.
"These drugs are not for every woman," notes ACSH's medical director, Gilbert Ross, M.D. "While these agents are relatively safe, there are potential adverse effects. But those with reason to believe they have an elevated risk of breast cancer may stand to benefit. Any woman with questions should consult a doctor they trust to advise them. Additionally, there are computerized tools available to help both patients and physicians assess the severity of risk." Adds Dr. Ross: "The large majority of women should not take any chemopreventive agent at this time, but current studies will give us a clearer picture of who will be the most likely to benefit."
Ms. Meister is a freelance writer, an associate editor of Nutrition Research Newsletter, and a former ACSH research associate.