english: In fact, the reason why 80 to 90 percent of those brain cancer surgeries ultimately fail is because of those small little extra margins that were left positive, those small little leftover tumors that were left there.
non_english: V skutočnosti, dôvod prečo 80 až 90 % z týchto operácií mozgu nakoniec neuspeje je to, že niektorý z týchto malých extra okrajov bol pozitívny, zostal tam malý zvyšok nádoru.