Tamoxifen (Nolvadex) Reduces Breast Cancer Risk

According to new findings from an Italian prevention trial, women with a high-risk of developing breast cancer can dramatically reduce their chances by taking the drug tamoxifen. Treatment however does not appear to benefit women at low risk for the disease.

Tamoxifen reduced the risks for women with specific high-risk factors of developing the type of breast cancer that is estrogen-dependent (ER+). It was associated with an 82% reduction in risk. The study is published in the Jan. 15 Journal of the National Cancer Institute. In the Italian study, women were considered to be at high risk for ER+ breast cancer if they had at least one functioning ovary, began menstruating at age 13 or younger, had not given birth before age 24, and were 5 feet 3 inches tall or taller. Study participants with all these characteristics who took tamoxifen were half as likely to develop breast cancer over a seven-year period as those who took placebo pills. Women who took hormone replacement therapy prior to and during the study period and had an increased risk for developing breast cancer significantly lowered their risks of developing breast cancer on tamoxifen therapy. They also discovered that tamoxifen had no effect on women who weren’t at high risk. Two other major studies from Britain and from the U.S, show tamoxifen protects high-risk women against breast cancer. ‘There is no inconsistency in the data about tamoxifen,’ says breast cancer prevention expert Victor G. Vogel, MD, who wrote an editorial assessing the Italian trial. ‘We now have three studies showing that this drug confers substantial reduction in risk for this subset of women. But tamoxifen isn’t for everybody, and we need to work on ways to identify the women that are most likely to benefit.’ Tamoxifen is most commonly used to prevent disease recurrence in women who have had breast cancer. However its use is associated with the formation of blood clots and cataracts, and long-term use has been linked to an increased risk of uterine cancer. . ‘One very important message is that every woman over 40 ought to discuss her level of risk with her physician,’ says Vogel, who directs the breast cancer prevention program at the University of Pittsburgh. ‘And the 15% to 20% of women who are truly at increased risk should be referred for a formal risk assessment to determine if they are candidates for preventive therapy.’ Vogel says tamoxifen, while effective, is not the ideal drug for preventing breast cancer. The osteoporosis drug Evista may be just as effective without increasing the risk of uterine cancer. The two drugs are currently being compared in a study involving approximately 19,000 women at high risk for breast cancer, and findings are expected in about four years. And a new class of drugs, known as aromatase inhibitors, is also showing promise as a preventive treatment in early trials. ‘It is a pretty safe bet that within the next few years, as the studies come in, preventive treatments will be safer and more effective,’ Vogel tells WebMD. (Source: WebMD Medical News)