Drugs to Prevent Breast Cancer Rarely Used

According to an article recently published in the Annals of Internal Medicine, medications that are effective in reducing the risk of developing breast cancer among women at a high risk for developing the disease are rarely used.

Breast cancer remains the second leading cause of cancer-related deaths among women in the United States. Previous studies have indicated that some drugs, such as tamoxifen and raloxifene, could reduce the risk of breast cancer among women who are at a high risk of developing the disease within their lifetime.

Tamoxifen and raloxifene are agents that block some of the effects of the female hormone,estrogen, on breast cells. They have demonstrated a reduction in the development of hormone-positive breast cancers, which are the most common types of cancers.

The United States Preventive Task Force (USPTF) released guidelines in 2002 suggesting that tamoxifen or raloxifen could be used to reduce the risk of developing breast cancer among women who are at a high risk of developing the disease within their lifetime. The United States Food and Drug Administration (FDA) also approved these 2 drugs for that specific indication; however, it is stressed that these drugs only be used among women whose benefits would outweigh the risks in their particular situation.

The Agency for Healthcare Research and Quality recently funded a large study to further evaluate data from prior trials regarding tamoxifen and raloxifene use in the prevention of breast cancer. The study included data from 7 previous trials identified as “good-and fair-quality trials” conducted from 2002 to 2012. The trials included women who received tamoxifen or raloxifene to reduce their risk of breast cancer and compared their outcomes to women who received placebo (sugar pill).

Women treated with tamoxifen or raloxifene had a reduced incidence of developing invasive breast cancer by 7 to 9 cases per 1,000 women over 5 years, compared to those who received placebo.
Data suggested that tamoxifen had a greater effect in reducing breast cancer than raloxifene.
Tamoxifen increased the risk of cataracts, uterine cancer and blood clots.
Tamoxifen and raloxifene reduced the risk of bone fractures.
Death from any cause, or death from breast cancer, was neither reduced nor increased among women who received tamoxifen or raloxifen compared to those received placebo.
The researchers concluded that tamoxifen “ reduced the incidence of invasive breast cancer and fractures and increased the incidence of thromboembolic events.” Longer follow-up may reveal long-term outcome differences between the groups of women.

It is important for women who are at a high risk of developing breast cancer to discuss their individual risks and benefits of treatment with tamoxifen or raloxifen for the prevention of the disease with their healthcare provider.

Reference: Nelson H, Smith M, Griffin J, Fu, R. Use of Medications to Reduce Risk for Primary Breast Cancer: A Systematic Review for the U.S. Preventive Services Task Force. Annals of Internal Medicine. 2013;158(8):604-614.