Background MONALEESA-3 demonstrated an overall survival (OS) benefit for ribociclib plus fulvestrant (R+F) in postmenopausal women with hormone receptor (HR) positive, HER2 negative advanced breast cancer (ABC). This study estimated quality-adjusted (QA) survival outcomes for patients receiving R+F vs. placebo (P)+F in MONALEESA-3. Methods Kaplan-Meier OS was partitioned into health states: (1) toxicity (TOX)=time spent with grade 3 –4 adverse events before progression