of course any recurrence of the brain cancer has poor prognosis. >> how much of knew row vascular problems are inherited? we know there's a history there in the biden family. how much does family history play a role? >> it's a great question. if you look at the rick factors aneurysm is not on the risk. smoking plays a role. sometimes working in certain factories, oil factories or paint factories which i don't think he's been involved we know that he was in iraq for about a year or so but those are probably not major risk factors. we don't really know. it's unknown ideology. >> the final question is it true that brain cancer is not as susceptible to other cancers to chemotherapy? the brain does not take in the