Im SA, et al. - In view of an earlier analysis suggesting a larger benefit on progression-free survival resulted from adding a cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor to endocrine therapy vs endocrine therapy alone in premenopausal or perimenopausal patients with advanced hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2)–negative breast cancer, researchers sought to describe the outcomes of the key secondary endpoint of overall survival. Either ribociclib or placebo in addition to endocrine therapy (goserelin and either a nonsteroidal aromatase inhibitor or tamoxifen) was randomly assigned to 672 patients included in the intention-to-treat population. Eighty-three deaths were reported among 335 patients (24.8%) in the ribociclib group and 109 deaths among 337 patients (32.3%) in the placebo group. As per outcomes, patients with advanced hormone-receptor–positive, HER2-negative breast cancer display significantly longer overall survival with a CDK4/6 inhibitor plus endocrine therapy vs endocrine therapy alone. No emergence of any new concerns regarding toxic effects with longer follow-up was observed.