The conditional survival statistics for survivors with primary supratentorial astrocytic tumors

Background. Relative survival rates can offer a general description of tumo r outcome and, traditionally, are used for surveillance and comparison purp oses. However, they are not informative for individual tumor survivors. Con ditional survival estimates can calculate the probability of surviving next some years given survival to a specific period of time after craniotomy fo r individual tumor survivors. However, clinically, they have not been used for predicting the tumor outcome. Methods. We calculated conditional probabilities of survival within 6 years after craniotomy in 112 patients with primary supratentorial astrocytic tu mors and evaluated factors affecting the survival time more than 2 years af ter craniotomy. Results. Our data showed that the conditional probability of survival can p redict yearly survival rate when patients survive for a specific period of time. The conditional survival rates within 6 years after craniotomy were a lways higher than those evaluated by relative survival rates. Overall, the longer the patients survived, the higher the conditional probabilities of s urviving sixth year postoperatively were. Conclusion. Our study demonstrates the conditional probabilities of surviva l have good availability and are important estimates for individual tumor s urvivors.