Forsythe A, et al. - Researchers reviewed studies of hormone receptor-positive (HR+)/human epidermal growth factor receptor 2- negative (HER2-) metastatic breast cancer (MBC) to evaluate progression-free survival (PFS) and other factors that influence overall survival (OS) and treatment response, and health-related quality of life (HRQoL), to ultimately determine if PFS a more relevant endpoint than OS in first-line HR+/HER2- MBC. Phase II and III randomized controlled trials (RCTs), observational, and retrospective studies searched from the Embase, Medline, and Cochrane databases were included. Significant improvements in OS was shown in few RCTs in HR+/HER2- MBC. Factors other than the choice of first-line (1L) therapy impact OS, including post-progression therapies, which could not be controlled in RCTs. Overall, the importance of PFS improvement in 1L treatment of HR+/HER2- MBC was emphasized.