Large Study of 3 Thousand Patients Finds Aspirin Ineffective in Breast Cancer Treatment

Aspirin is a widely used medicine that has treated and prevented many diseases throughout history. It is particularly known for its beneficial effects on cardiovascular disease and certain cancers. Observational studies have supported potential benefits of aspirin in treating a common and serious disease such as breast cancer. However, these benefits need to be confirmed by prospective studies. In this context, a study published in JAMA investigated aspirin use in patients with high-risk, nonmetastatic (early-stage) breast cancer and its effects on disease-free survival. Its results provide important findings that call this treatment's effectiveness into question.

Study Details

An interim analysis of the phase III Alliance A011502 study, conducted by Dr. Wendy Y. Chen and colleagues and published in JAMA, showed that adjuvant aspirin did not improve invasive disease-free survival compared with placebo in patients with high-risk, nonmetastatic breast cancer. The study was stopped early for futility.

Key Findings

• Study Design: Between January 2017 and December 2020, 3,020 patients from centers in the United States and Canada were randomized to aspirin 300 mg once daily (1,510 patients) or placebo (1,510 patients). Patients had to have completed all local treatment and chemotherapy; continuing endocrine therapy was permitted. The primary outcome was invasive disease-free survival.
• First Interim Analysis: The data and safety monitoring committee recommended stopping the study at the first interim analysis after the hazard ratio (HR) for invasive disease-free survival crossed the prespecified futility boundary. At this analysis, with a median follow-up of 33.8 months (range = 0.1–72.6 months), invasive disease-free survival events occurred in 141 patients in the aspirin group and 112 in the placebo group (HR = 1.27, 95% confidence interval [CI] = 0.99–1.63, P = 0.06).
• Survival Data: Differences in invasive disease-free survival events between the aspirin and placebo groups were not statistically significant. There were 63 deaths in the aspirin group and 52 in the placebo group (HR = 1.19, 95% CI = 0.82–1.72, P = 0.36). A total of 81 deaths were attributed to breast cancer: 46 in the aspirin group and 35 in the placebo group.
• Adverse Events: Grade ≥ 3 adverse events occurred in 9.3% of patients in the aspirin group and 10.2% in the placebo group. Vascular events were the most common adverse events in both groups (1.8% versus 1.5%). Dose reductions to 100 mg because of adverse events occurred in 2.3% of the aspirin group and 2.2% of the placebo group.

Conclusion

The researchers stated that daily aspirin did not improve breast cancer recurrence or survival risk during early follow-up in participants with high-risk, nonmetastatic breast cancer. Despite being widely available and accessible, aspirin should therefore not be recommended as adjuvant breast cancer treatment.