Medications to lower breast cancer risk
Healthy, high-risk women may benefit from medications to lower their risk for breast cancer. The two types of medications may be used to lower the risk for breast cancer in women; selective estrogen receptor modulators (SERM) and aromatase inhibitors.
Most of the research on these medications have looked at women with increased risk for breast cancer due to a family history of cancer or certain breast changes found on biopsy. There has been very little research on how well these medications work in women with an inherited mutation linked to breast cancer risk.
High-risk women who wish to consider medications to lower their risk for breast cancer should discuss the benefits, risks and limitations with their health care provider.
The two most commonly used SERMs are tamoxifen and raloxifene.
- Tamoxifen blocks the effect of estrogen on breast tissue. Tamoxifen is approved for use in both pre- and post-menopausal women. When taken for five years, it reduces breast cancer risk by up to 40%; this protective effect continues beyond the five-year treatment period. Tamoxifen may also protect bone density and reduce risk in postmenopausal women who cannot take hormone replacement therapy. Side effects of tamoxifen include an increased risk of endometrial cancer and blood clots.
- Raloxifene works in a similar way as tamoxifen. It is used to lower breast cancer risk in postmenopausal women. Raloxifene has a lower risk for endometrial cancer and blood clots and fewer side effects than tamoxifen. The most common side effects are hot flashes, blood clots, nausea and weight gain.
Aromatase inhibitors are medications that block production of estrogen in postmenopausal women. Common aromatase inhibitors include anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin).
Unlike SERMs, aromatase inhibitors do not improve bone density. In fact, they may actually accelerate bone loss in postmenopausal women. However, aromatase inhibitors tend to cause fewer side effects and do not appear to have the risk of blood clots or endometrial cancer seen with tamoxifen.
No studies have looked at aromatase inhibitors for the prevention of breast cancer in women with an inherited mutation linked to breast cancer.
The following are breast cancer screening or prevention studies enrolling people at high risk for breast cancer.
- NCT04711109: Denosumab for Preventing Breast Cancer in Women with a Inherited Mutation (BRCA-P). This study will test the effectiveness of a drug (denosumab) on preventing the development of breast cancer in women with an inherited mutation.
- NCT04067726: Denosumab and Mammographic Density in Premenopausal Women With Dense Breasts (TRIDENT). This study is looking at the drug denosumab to learn if it can reduce breast density in high-risk premenopausal women who have dense breasts.
- The Risk Factor Analysis of Hereditary Breast and Ovarian Cancer In Women with , or Mutations. This study seeks to improve researchers’ understanding of how hormonal, reproductive and lifestyle factors may be associated with cancer in high-risk people.
- NCT02620852: Women Informed to Screen Depending on Measures of Risk (WISDOM) study. The goal of this study is to determine if breast cancer screening can be made better by personalizing each woman’s schedule, compared to the current one-size-fits-all, annual approach.
- NCT03729115: A Multi-Modality Surveillance Program for Women at High Risk for Breast Cancer is a clinical trial at the University of Chicago that is enrolling women age 21 and older who are , , , or carriers for an and anxiety reduction trial.
Additional risk-management clinical trials for people at high risk for breast cancer may be found here.