Time-to-event has become one of the primary endpoints of many clinical trials. Comparing treatments and therapies using time-to-event (or “survival”) data requires some care, since survival differences may occur either early or late in the follow-up period, depending on various factors such as the initial potency or the duration of efficacy of the drugs. In this work, we investigate the effect of the CIMAvax?EGF vaccine therapy on the survival of patients with non-small cell lung cancer, using stratified and unstratified weighted log-rank tests. Weighted log-rank tests are designed to identify early and late survival differences between treatments. Using these tests, we conclude that the vaccine is more efficient than the standard therapy among patients less than 60 years of age.