Howie LJ, Singh H, Bloomquist E, et al. - Researchers investigated whether the combination of a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor and an aromatase inhibitor (AI) is safe and effective in older women with hormone receptor–positive, human epidermal growth factor receptor 2–negative metastatic breast cancer. In this pooled analysis, data from 3 randomized controlled studies (N = 1,827) were analyzed, wherein, postmenopausal women with hormone receptor–positive, human epidermal growth factor receptor 2–negative metastatic breast cancer were treated with different CDK4/6 inhibitors in combination with an AI for initial therapy. Findings revealed similar efficacy with a CDK4/6 inhibitor in combination with an AI vs AI alone for first-line treatment of breast cancer in the older women vs younger patients. Higher rates of toxicity, dose modifications, and a reduction from baseline in quality-of-life measures were observed in patients older than age 75 years.