Correlation between progression-free survival and overall survival in metastatic breast cancer patients receiving anthracyclines, taxanes, or targeted therapies: a trial-level meta-analysis.

Over the past decade, several new drugs have received regulatory approval for metastatic breast cancer (MBC). However, some of these approvals were based on improvement in progression-free survival (PFS), without a concomitant increase in overall survival (OS). This has led some to question the utility of using PFS as a measure for drug approval.