The United States Preventive Services Task Force (USPSTF) has published draft recommendations for the use of medications for primary risk reduction of breast cancer in high-risk women.
Based on review of the existing evidence, the Task Force recommends that clinicians discuss preventive therapy using tamoxifen or raloxifene with their patients at increased risk for breast cancer and offer these therapies for women whose potential benefit outweighs their risk of medication-related adverse events.1,2
Preventive therapy should be considered only for those who, because of family history or other risk factors, are considered to have a higher than average risk for developing invasive breast cancer. Typically, a formal risk assessment, is based on the National Cancer Institute (NCI) Breast Cancer Risk Assessment Tool,3 although other tools are also available. The NCI tool predicts 5-year cancer risk based on the individual’s age, first-degree family history, ethnicity, age at first menarche, age at first live childbirth, and personal history of ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), or breast biopsies. It is important to note that none of the existing risk assessment tools is recommended for risk assessment of women who have already had breast cancer or whose family history includes BRCA1 or BRCA2 mutations.1
The recommendations are limited to women between the ages of 40 and 70, with no prior diagnosis of invasive breast cancer, LCIS, or DCIS, and no history of blood clots or stroke.1
In the accompanying meta-analysis performed for the USPSTF recommendations, both treatments reduced the risk of invasive breast cancer by 30% to 56%.2 The principal serious harms associated with treatment are thromboembolic events and, for women with an intact uterus, increased risk for endometrial cancer associated with tamoxifen use.2 Younger women are at less risk for thromboembolic events.1
Based on the NCI tool and using 5-year risk-to-benefit tables developed by Freedman, the Task Force estimates that many women whose 5-year risk is 3% or greater will derive more benefit than harm from preventive therapy with tamoxifen or raloxifene.1,4 Individual factors including age, race or ethnicity, intact uterus, and the medication chosen influence the balance of benefit and harm and should be accounted for in making treatment decisions with patients.1
The recommended doses for primary prevention are tamoxifen 20 mg or raloxifene 60 mg daily for 5 years. Although other agents are being studied for breast cancer prevention in this same population, notably exemestane, they are not Food and Drug Administration–approved for this indication and are not included in the recommendation).1
Assessment of breast cancer risk provides an opportunity for patient education; the women who are truly at increased risk may be unaware of the option for preventive therapy. These new recommendations should help to raise awareness of the potential for primary prevention and provide a framework for healthcare practitioners and high-risk women to make informed decisions about preventive therapy.
1. U.S. Preventive Services Task Force. Medications for Risk Reduction of Primary Breast Cancer in Women: US Preventive Services Task Force Recommendation Statement. Draft, April 16, 2013. http://www.uspreventiveservicestaskforce.org/draftrec4.htm. Accessed April 22, 2013.
2. Nelson HD, Smith B, Griffin JC, Fu R. Use of medications to reduce risk for primary breast cancer. A systematic review for the U.S. Preventive Services Task Force. Ann Intern Med. 2013;158(8):604-614.
3. National Cancer Institute. Breast Cancer Risk Assessment Tool. http://www.cancer.gov/bcrisktool/. Accessed April 22, 2013.
4. Freedman AN, Yu B, Gail MH, et al. Benefit/risk assessment for breast cancer chemoprevention with raloxifene or tamoxifen for women age 50 years or older. J Clin Oncol. 2011;29(17):2327-2333.