Adjuvant denosumab in early breast cancer: Disease-free survival analysis of 3,425 postmenopausal patients in the ABCSG-18 trial.

500Background: Adjuvant aromatase inhibitors (AI) are standard of care for postmenopausal women with hormone receptor positive (HR+) early stage breast cancer but cause osteoporosis and fractures. ABCSG-18 showed previously that adjuvant denosumab significantly reduces clinical fractures (primary endpoint, HR = 0.5, p < 0.0001, Lancet 2015). Here, we present the impact of adjuvant denosumab on disease-free survival. Patients and Methods: 3,425 postmenopausal patients with early HR+ BC receiving adjuvant AI were recruited in 58 trial centers into this prospective, double-blind, placebo-controlled, phase-III trial. Patients were randomized 1:1 to receive either denosumab 60mg s.c. (N = 1712) or placebo (N = 1713) q6 months during AI therapy. We here present results of ABCSG-18’s secondary endpoint disease-free survival (DFS), including relevant subgroup and sensitivity analyses (accounting for cross-over either by censoring or by using a rank preserving structural failure time model). Results: After a media...