Median Survival Definition

Median Survival Time

Median survival time is defined as the time from either diagnosis or treatment at which half of the patients with a given disease are found to be, or expected to be, still alive.  In a clinical trial, median survival time is one way to measure how effective a treatment is.  Also called median overall survival and median survival.  This method is used because it is often too difficult to wait until all patients have died in order to calculate an "average" survival based on all patients.