Progression-Free Survival

A new hobby of mine is occasionally reading trial reports on the treatments prescribed to my wife. In those studies two important measures are progression-free survival (PFS) and overall survival (OS). The first is the number of months until cancer ceases to be arrested by treatment and resumes growing and spreading, and the second is the number of months until death. So it is that such reports will contain sentences such as the one that today caught my mind: “METEOR [the name of the trial] employed a novel trial design to allow for appropriate statistical power for both a primary endpoint of progression-free survival and a secondary endpoint of overall survival while avoiding over-representation of rapidly-progressing patients for the primary endpoint.”

“Rapidly-progressing patients.” Without knowing the context already, I would have mistakenly taken that to mean patients who are getting better, and that the statisticians were taking measures to not over-represent favorable outcomes. Instead it means just the opposite: rapidly-progressing patients are rapidly progressing toward death. It felt contradictory, this notion of rapid progress as a bad thing and being progression-free as a good thing.

As readers of this Jr. Ganymede site, however, you are probably well familiar with the notion that much of what is labeled progressive is progressive toward death, even though dressed in language coaching us that the progress is doubleplusgood. The notion of progression-free survival probably has a familiar feel to it as well. Wishing you all freedom from the cancers that metastasize and disable our society and comfort amid the pain and sadness they cause.