HealthDay News — The U.S. Preventive Services Task Force (USPSTF) is recommending women at increased risk of breast cancer and low risk for side effects be prescribed primary prevention drugs.

The Task Force gave risk-reducing drugs such as tamoxifen and raloxifen a grade B endorsement for women aged 35 and older with no prior breast cancer, ductal carcinoma in situ or lobular carcinoma in situ, according to a Recommendation Statement published online in Annals of Internal Medicine.

In contrast, chemoprophylaxis got a grade D recommendation against use for asymptomatic women with low or average breast cancer risk — a recommendation that remains unchanged from the last USPSTF recommendations issued in 2002.

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Since then the USPSTF has conducted a systematic review to assess the effectiveness, adverse effects and subgroup variations of medication to reduce breast cancer risk. They specifically focused on the selective estrogen receptor modulators tamoxifen and raloxifene, and reviewed a meta-analysis of placebo-controlled trials to assess the benefits and harms of these medications.

Tamoxifen and raloxifene cut incidence of invasive breast cancer by seven to nine events per 1,000 women over five years, with tamoxifen being more effective in that regard than raloxifene, the researchers found.

Both medications had “adequate” evidence to support risk reduction for nonvertebral or vertebral fractures in postmenopausal women. However, only raloxifene is approved for breast cancer prevention in postmenopausal women. Tamoxifen is indicated for women aged 35 years and  older regardless of menopausal status.

These medications are not without adverse events, USPSTF cautioned. Both drugs had “adequate” evidence that they increased the risk for venous thromboembolic events by four to seven events per 1,000 women over five years, with tamoxifen raising the risk more than raloxifene.

Tamixfen also raises endometrial cancer risk by four cases per 1,000 women and may contribute to the development of cataracts, according to the Task Force.

Based on the findings, the researchers recommend that clinicians engage in shared, informed, decision making for women aged 35 years or older, at risk of breast cancer.

Other adverse events associated with these medications include hot flushes that may impact quality of life and willingness to adhere to the medications, they added.

“While these medications have some significant side effects, it is important that clinicians and women at high risk for breast cancer be aware of the options these drugs offer,” USPSTF member Wanda Nicholson, MD, MPH, MBA, said in a statement.


  1. Moyer VA. Ann Intern Med. 2013; doi:10.7326/0003-4819-159-10-201311190-00718.