Progression-free survival

Progression-free survival (PFS) is a measure of the activity of a treatment on a disease. It is the time that passes from a certain date (generally the first day of treatment, or the day in which a patient is enrolled in a clinical trial) and the date on which disease "progresses" or the date on which the patient dies, from any cause. In Oncology, PFS usually refers to situations in which a tumor is present, as demonstrated by laboratory testing, radiologic testing, or clinically. (a similar term that applies to patients that have had operations and are left with no detectable disease, is Disease-Free Survival).