Medication Use to Reduce Risk of Breast Cancer: US Preventive Services Task Force Recommendation Statement.
Level 1 - systematic review of randomized trials
Practice guideline based on a systematic review of randomized trials and observational studies.
PubMed 31479144 · doi:10.1001/jama.2019.11885
What was done
The US Preventive Services Task Force (USPSTF) updated its 2013 recommendation on medications for primary breast cancer risk reduction. They reviewed evidence from randomized controlled trials, observational studies, and diagnostic accuracy studies assessing risk assessment tools and the effectiveness, harms, and subgroup variations of tamoxifen, raloxifene, and aromatase inhibitors in asymptomatic women 35 years and older without prior breast cancer or ductal carcinoma in situ (DCIS).
What was found
The abstract reports no numerical risk estimates or effect sizes. It found that risk assessment tools reliably predict population-level breast cancer incidence but perform modestly at discriminating individual risk. Convincing evidence showed that tamoxifen, raloxifene, or aromatase inhibitors provide at least moderate benefit in reducing invasive estrogen receptor-positive breast cancer in postmenopausal women at increased risk, while benefits are no greater than small in women at average risk. Tamoxifen and raloxifene demonstrated convincing evidence of small-to-moderate harms, and aromatase inhibitors showed adequate evidence of small-to-moderate harms. Consequently, the USPSTF recommends offering these medications to women at increased risk of breast cancer and low risk for medication harms (Grade B), and recommends against routine use in women not at increased risk (Grade D).
Why it matters
This guideline defines clinical practice for primary chemoprevention in primary care, advising clinicians to reserve tamoxifen, raloxifene, or aromatase inhibitors for women with demonstrated high baseline risk where preventive benefits outweigh medication toxicities.
Limits
The abstract provides qualitative summary statements without specific numerical risk ratios, absolute risk reductions, or adverse event incidence rates. Risk prediction tools showed only modest accuracy for individual risk discrimination. The recommendations exclude women with existing or prior breast cancer or DCIS, and the abstract does not specify the exact risk thresholds used to define increased risk.