treatments. he was at md anderson. the worst brain cancers, the average survival is 15 months right now, alisyn. so these are tough figures. it often strikes at the stage of life. >> i was reading brain cancer's like beau biden kills 15,000 americans a year. are they usually fatal? >> they are usually fatal. the worst type again is the most aggressive 15 monthst the survival. there are others that are lower grade, mean they're not as aggressive. where people can survive longer. they can use viral-based genetic therapies, the radiation therapies are the best shot we have. sometimes they provide more months at life. they haven't been able cure these tumors. >> how terrible.