Progression-free survival as an end-point in solid tumours--perspectives from clinical trials and clinical practice.

Progression-free survival (PFS) is an end-point in an increasing number of cancer clinical trials, informing both regulatory bodies and clinical practice. PFS is utilised both as a surrogate end-point for overall survival and as a primary trial end-point in itself. Understanding the history of clinical trial definitions of progression provides some context for how PFS may be applied to clinical practice as well as some of its limitations that need to be considered in patient care decisions. This commentary reviews recent drug approval for anti-cancer agents in solid tumours, reviews various concepts of progression in clinical trials and outlines some future directions for patient care and clinical trial research using progression free survival.