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: Daardoor mislukt uiteindelijk 80 tot 90% van hersenkankeroperaties. Omwille van die kleine marges  die men neemt, de kleine stukjes tumor  die men laat steken.