USPSTF Reaffirms Drugs for Women at High Risk for Breast Cancer

Roxanne Nelson, RN, BSN

January 15, 2019

In a new draft recommendation, the US Preventive Services Task Force (USPSTF) has reaffirmed its support for chemoprevention with tamoxifen (multiple brands) and raloxifene (Evista, Lilly) for women at increased risk for breast cancer and has added aromatase inhibitors (AIs) to its recommendation.

The inclusion of AIs is the primary difference between the new draft guidelines and the previous recommendations, issued in 2013.

However, only raloxifene and tamoxifen have been approved by the US Food and Drug Administration as chemoprevention for this indication, and raloxifene is only indicated for use in postmenopausal women.

The recommendations are supported by data from clinical trials that show that chemoprevention in women at high risk reduces the incidence of invasive breast cancer.

A systematic review conducted for the USPSTF found that, compared to placebo, tamoxifen reduced the incidence of invasive breast cancer by seven events per 1000 women over 5 years, raloxifene reduced the incidence by nine events per 1000 women over 5 years, and AIs reduced the incidence by 16 events per 1000 women over 5 years.

The absolute benefits are likely even higher for women with a predicted breast cancer risk of 3% or greater, the task force notes.

"Too many American women and families are faced with the challenge of dealing with a breast cancer diagnosis," said USPSTF member Michael J. Barry, MD, director of the Informed Medical Decisions Program in the Health Decision Sciences Center at Massachusetts General Hospital, Boston.

"Women who are at increased risk for breast cancer should be offered medications that can help reduce that risk," he explained in a statement.

Potential Harms for Intervention

Both tamoxifen and raloxifene are associated with small to moderate harms, including an increased risk for venous thromboembolic events (VTEs), the task force notes. Tamoxifen poses a higher risk for VTEs, with the risk greater in older than in younger women. Tamoxifen can increase the risk for endometrial cancer in women with a uterus; this risk was not observed for raloxifene. Tamoxifen may also increase the risk for cataracts. In addition, vasomotor symptoms are a common adverse effect of both drugs.

The harms of AIs, which were found to be small to moderate, include vasomotor symptoms, gastrointestinal symptoms, musculoskeletal pain, and cardiovascular events, such as stroke. In addition, AIs do not reduce, and may even increase, the risk for fractures.

The task force emphasizes that the potential benefit of risk reduction of breast cancer must be balanced against the potential harms of adverse effects. Thus, the task force advises the use of these drugs for women who at increased risk for breast cancer and who are also at low risk for adverse medication effects (B recommendation).

Conversely, women who are not at increased risk for breast cancer should not be routinely offered chemoprevention with these drugs, because the risk for harms likely outweighs their potential benefit (D recommendation).

"These medications are not for everyone, and for women who are not at increased risk of breast cancer, the harms of these medications are likely to outweigh the benefits," said USPSTF member Carol M. Mangione, MD, MSPH, professor of medicine and public health at the David Geffen School of Medicine at the University of California, Los Angeles.

"When deciding whether or not to offer medications, clinicians should carefully consider their patients' risk factors for breast cancer and balance these against the potential harms from the medications," Mangione added in a statement.

The task force's draft recommendation statement and draft evidence review have been posted for public comment on the USPSTF website. Comments can be submitted online from January 15 to February 11, 2019.

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