Extended letrozole improves disease-free survival in hormone receptor-positive breast cancer: 15-year results
Published on 24 October 2026
Prof Eleftherios Mamounas talks to ecancer at ESMO 2026 about the final analysis of the phase III NSABP B-42 trial, evaluating extended adjuvant letrozole in postmenopausal women with hormone receptor-positive breast cancer.
The study randomised 3,966 patients who had completed five years of endocrine therapy to receive an additional five years of letrozole or placebo.
After a median follow-up of 15.9 years, extended letrozole significantly improved disease-free survival (61.6% versus 56.5%; HR 0.85), reduced distant recurrence (6.9% versus 9.7%) and improved breast cancer-free interval.
However, no significant overall survival benefit was observed (HR 0.92).
The findings demonstrate a sustained benefit from extended letrozole therapy, with no attenuation of treatment effect between 10 and 15 years of follow-up.