Progression-free survival

Progression-free survival (PFS) is "the length of time during and after the treatment of a disease, such as cancer, that a patient lives with the disease but it does not get worse". In oncology, PFS usually refers to situations in which a tumor is present, as demonstrated by laboratory testing, radiologic testing, or clinically. Similarly, "disease-free survival" is the length of time after patients have received treatment and have no detectable disease.

Time to progression (TTP) does not count patients who die from other causes but is otherwise a close equivalent to PFS (unless there are many such events). The FDA gives separate definitions and prefers PFS.