Informative censoring of surrogate end-point data in phase 3 oncology trials.

Background: Kaplan-Meier (K-M) analysis, the cornerstone of cancer clinical trial interpretation, assumes that censored patients are no more or less likely to experience an event than those followed. We sought to investigate the patterns of censoring in surrogate end-points of oncology randomised controlled trials (RCTs) and examine the relationship between censoring in practice-changing treatments that failed to demonstrate survival gain.

Methods: In this cross-sectional study of phase III RCTs published in the New England Journal of Medicine, Lancet, and JAMA, between 2010 and 2020, K-M curves of surrogate end-points with statistical significance were extracted.