Difference Between Duration Of Treatment (Dot) And Progression-Free Survival (Pfs) As A Marker Of Unbalanced Censoring.

2548 Background: In the conduct of randomized trials Kaplan and Meier envisioned rates of censoring as similar between arms, providing accurate assessment of clinical trial results. Censoring is used when patients withdraw consent, leave study due to toxicity, or reach data cut-off without disease progression or death. Censoring can lead to erroneous conclusions as it can be either beneficial or detrimental to the arm under study. Such censoring can also explain how a statistically valid difference in PFS “disappears” when overall survival (OS) is examined. We hypothesized that censoring, especially that due to toxicity, would lead to a discrepancy between DOT and PFS since two different patient populations would be scored. Methods: We reviewed all phase III randomized studies of drugs approved by FDA since 2005 for pts with metastatic solid tumors, looking for DOT and PFS. We used standard statistical analyses using SAS. Results: We identified 55 Phase III studies conducted with abiraterone, axitinib, be...