In an update to its recommendations from 2002, the United States Preventive Services Task Force (USPSTF) continues to recommend the use of breast cancer primary prevention drugs for higher-risk women. However, they re-emphasized the advice that women who are not at an increased risk of developing breast cancer should not be using such medications as tamoxifen or raloxifene.
These recommendations are based on a systematic review which found that tamoxifen and raloxifene resulted in lower incidence of invasive breast cancer by seven to nine events per 1000 women over a five-year period. Tamoxifen was more effective in breast cancer prevention, but both drugs were found to be effective in reducing risk of fractures in postmenopausal women. However, both drugs were found to put women at increased risk of blood clots and hot flashes, making them more difficult to use. Tamoxifen was also found to increase the risk of endometrial cancer.
The task force emphasizes that Only a small fraction of women are at an increased risk for breast cancer; moreover, only a subset of those women will derive benefit from risk-reducing medications. But Dr. Clifford A. Hudis, chief of breast cancer medicine at Memorial Sloan-Kettering Cancer Center in New York City, president of the American Society of Clinical Oncology, and an ACSH advisor, notes, The more that people promulgate clear guidance for how these drugs should be used and the more people are aware of the potential to really prevent cancer, it should be really useful.
Other organizations have also arrived at similar recommendations. The American Society of Clinical Oncology recommends the use of tamoxifen for women 35 years or older who are at an elevated risk of developing breast cancer. For postmenopausal women, they also add the option of using raloxifene or exemestane (Aromasin). The Canadian equivalent of the USPSTF recommends talking to women at an increased risk of developing breast cancer about the risks and benefits of taking tamoxifen, and like our own panel recommends against the use of this drug by normal or low-risk women. And the British National Institute for Health and Care Excellence (NICE) recommends tamoxifen or raloxifene for high-risk,postmenopausal women, over a five-year period, excluding those women who are at an increased risk of developing thromboembolic disease or endometrial cancer.