Key clinical point: In postmenopausal women with early-stage hormone receptor-positive (HR+) breast cancer (BC) who were disease free after 5 years of endocrine therapy (ET), extended adjuvant treatment with letrozole for 5 years led to improved disease-free survival (DFS) at >10-year median follow-up.
Major finding: After median follow-up of 10.3 years, letrozole vs placebo significantly improved DFS (10-year absolute benefit 3.4%; hazard ratio 0.85; P = .01). There were no notable differences in toxicity outcomes between the groups.
Study details: Findings are from the phase 3 National Surgical Adjuvant Breast and Bowel Project B-42 trial including 3966 postmenopausal women with stage I-IIIA HR+ BC who were disease free after 5 years of adjuvant ET and were randomly assigned to receive letrozole or placebo for 5 more years.
Disclosures: This study was funded by Novartis and others. Some authors declared receiving grants, honoraria, travel support, or consulting fees or serving on advisory boards or data and safety monitoring boards for various sources, including Novartis.
Source: Mamounas EP et al. Ten-year update: NRG Oncology/NSABP B-42 randomized trial: Extended letrozole therapy in early-stage breast cancer. J Natl Cancer Inst. 2023 (May 15). doi: 10.1093/jnci/djad078