By Will Boggs MD

NEW YORK (Reuters Health) – Women with a high risk of developing breast cancer can lower that risk by taking certain medications, according to updated recommendations from the US Preventive Services Task Force (USPSTF).

“The Task Force encourages women to talk about the benefits and harms of medication with their clinicians so they can make the best choice for themselves, based on their personal values and preferences,” USPSTF Task Force member Dr. Michael Barry from Harvard Medical School in Boston, told Reuters Health by email.

Drawing on findings in more than 5 million women who participated in 46 studies, USPSTF issued two main recommendations in its 2019 updated statement.

First, women with no personal history of breast cancer but at a high risk for developing it should consider taking medications to reduce their risk of breast cancer, especially if they have a low risk of developing unwanted side effects.

Figuring out whether you’re one of those high-risk women is not straightforward. The Task Force statement mentions a couple of risk assessment tools but stops short of endorsing them because evidence shows they’re not accurate for all women. Instead, the Task Force suggests that women with at least a 3% risk for breast cancer in the next 5 years are likely to benefit from risk-reducing medications and should be offered them if their risk of harm from the drugs is low.

Second, the USPSTF recommends against using such medications for women who don’t have an increased risk of breast cancer (including women younger than 60 years with no additional risk factors for breast cancer), because the likelihood of side effects from the medications (like blood clots, endometrial cancer, and cataracts) probably outweighs the potential breast cancer prevention benefit.

The previous recommendation, in 2013, included tamoxifen and raloxifene as risk-reducing medications. The 2019 update includes those and adds a class of medications called aromatase inhibitors (including exemestane and anastrozole) to that list. They note, however, that aromatase inhibitors are not currently approved by the US Food and Drug Administration (FDA) for reducing the risk of breast cancer.

The Task Force recognizes that women with mutations in the breast cancer genes BRCA1 and BRCA2 and women who previously received chest radiation face an increased risk of breast cancer, but there is not enough evidence on the benefits and harms of these medications to make a sound recommendation for these women.

“Additionally,” Dr. Barry said, “we also need more evidence to better understand the lifelong benefits and harms of these medications and how they can reduce risk in specific populations, such as African-American women who are more likely to die of breast cancer.”

“While the Task Force encourages women to talk to their clinicians about their likelihood for developing breast cancer, the evidence did not clearly demonstrate a specific frequency for this assessment,” he added. “Women might repeat risk assessments with their clinicians if there is a change in their risk factors, such as if a family member is newly diagnosed with breast cancer.”

“The Task Force continues to recommend that women who are concerned about their chances for developing breast cancer talk to their clinician to decide if preventive medications are right for them,” Dr. Barry said.

Dr. Heidi D. Nelson from Oregon Health and Science University, Portland, Oregon, who co-authored the evidence review that supports the recommendations, told Reuters Health, “Various risk criteria were used to enroll women into trials of risk-reducing medications. These criteria usually included family history of breast cancer and previous benign breast biopsy, particularly atypical hyperplasia. Results of the trials may be most applicable to women with similar risks as the trial participants.”

Dr. Lydia E. Pace from Brigham and Women’s Hospital, Boston, co-authored an editorial related to this report. She told Reuters Health by email, “I have cared for patients who do really well with risk-reducing medications and feel good about their decision to take them. I have other patients who have not tolerated them and need to stop after a short time. And I’ve had patients who strongly don’t want to take a new medication every day for 5 years and don’t feel the potential benefit is worth it.”

“Decisions about these medications are often not clear-cut and I try to convey that, as long as women are informed, all of these decisions are okay,” she said. “It’s also important for women to remember that there are other important ways that they can reduce breast cancer risk, including reducing alcohol intake and maintaining a healthy weight.”

The complete recommendation statement, evidence review, editorials, and patient page appear in the Journal of the American Medical Association.

SOURCE:,,, and Journal of the American Medical Association, online September 3, 2019.