Progression-Free Survival: Meaningful or Simply Measurable?

The last few years have seen an increase in the number of randomized controlled trials (RCTs) of new agents in metastatic solid tumors using progression-free survival (PFS) as the primary end point. Some trials showing improvement in PFS, without a correspondingincreaseinoverallsurvival(OS),haveledtoapprovalofnew drugs and/or changes in standard of care. This suggests a growing belief in the oncology community that delaying progression in metastaticdiseaseisaworthygoal,evenifOSisnotimproved.Butisanew treatment that improves PFS really an advance for patients? Or is it only lowering the bar to declare active some of our much-heralded new molecular targeted therapies? We believe that as a community, this trend requires discussion and debate.