Clinicians should offer medications that may reduce the risk of breast cancer in postmenopausal women who are at high risk for breast cancer, but these medications should not be routinely offered for women who are not at increased risk, according to the U.S. Preventive Services Task Force (USPSTF).
There is a “moderate benefit” of medications such as tamoxifen, raloxifene (Evista), or aromatase inhibitors for cutting risk of invasive estrogen receptor (ER)-positive breast cancer in women at increased risk for breast cancer, and low risk for adverse medication effects (B recommendation), according to the task force members in a draft recommendation statement on the USPSTF website. The draft is open for public comment through Feb. 11, 2019.
However, the group recommends against the routine use of these medications in women not at increased risk for breast cancer (D recommendation).
These recommendations are “consistent” with those from 2013, though aromatase inhibitors have been added as a medication clinicians may consider since the last time the task force addressed the subject, the authors noted.
“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,” said task force member Carol M. Mangione, MD, in a statement.
Indeed, for women who are not at increased risk for breast cancer, the task force only found a “small benefit” in reducing risk for breast cancer, but noted that the medications are linked with “moderate harms,” and concluded with “moderate certainty” that these risks outweigh the benefits.
In 2018, about 266,000 new cases of breast cancer were diagnosed in women in the U.S. (30% of all new cancer cases in women), the authors said. Moreover, almost 41,000 women died of breast cancer (14% of all cancer deaths in women). The 5 year-survival rate is estimated at 89.7%, the authors said, but mortality rates are higher among black women, despite similar incidence rates as white women. In addition, incidence rates have increased among Asian/Pacific Islander, non-Hispanic black, and Hispanic women, they wrote.
Women defined as being at an increased risk for breast cancer include:
- Atypical ductal or lobular hyperplasia or lobular carcinoma in situ on a prior biopsy
- Age ≥65 with one first-degree relative with breast cancer
- Age ≥45 with more than one first-degree relative with breast cancer or one first-degree relative who developed breast cancer at age <50
- Age ≥40 with a first-degree relative with bilateral breast cancer
The task force reported “convincing evidence” that tamoxifen and raloxifene are associated with small to moderate harms. Both agents increase the risk for venous thromboembolic events (VTEs), although tamoxifen increases risk more than raloxifene, especially in older women versus younger women.
There also is “adequate evidence” that tamoxifen alone increases the risk for endometrial cancer in women with a uterus. The agent also increases the risk of cataracts.
Vasomotor symptoms (hot flashes) are a common adverse effect of both medications, according to the authors.
Aromatase inhibitors, which were added as a medication option in this statement, were studied in two trials of 10 that evaluated the effect of risk-reducing medication in post-menopausal women at increased risk for breast cancer. Pooled analyses found that use of aromatase inhibitors would result in 16 fewer cases of invasive breast cancer (RR 0.45, 95% CI 0.53-0.70) and 15 fewer cases of ER-positive breast cancer (RR 0.37, 95% CI 0.19-0.63).
However, the authors noted that comparisons of effectiveness between the three medication types “cannot be made because of the different participant characteristics among the placebo-controlled trials.”
More research is needed to evaluate how medications could reduce breast cancer risk in women who are carriers of BRCA1 or BRCA2 mutations. Given higher mortality rates among black women, the task force said that studies with “sufficient numbers of black women” are needed. They also called for longer-term follow-up on studies of raloxifene and aromatase inhibitors.
Mangione and co-authors disclosed no relevant relationships with industry.