Examining the informativeness of premature censoring in evaluating progression-free survival
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*Mark Rothmann, FDA 

Keywords: progression-free survival, overall survival, censoring

According to the intent-to-treat principle, analyses should be based on the grouping of patients as they were randomized and all patients should be followed to the endpoint or the end of study. For an unbiased comparison with valid p-values, an intent-to-treat analysis is essential. Increasingly in oncology, progression-free survival (PFS) is used as an approval endpoint. It can be difficult to have a meaningful intent-to-treat analysis of PFS. There have been registration studies having extensive loss-to-follow-up for PFS. From using remaining overall survival as a surrogate for remaining PFS we see that premature censoring is generally informative and indicative of worse prognosis or similar prognosis (not better prognosis) for remaining life than those patients in the same arm for which follow-up for PFS continues.