Researchers at the University of Sydney have uncovered a mechanism that may explain why glioblastoma returns after treatment, and the world-first discovery offers new clues for future therapies. Glioblastoma is one of the deadliest brain cancers, accounting for about half of all brain tumors, with a median survival rate of just 15 months. Despite surgery and chemotherapy, more than 1,250 clinical trials over the past 20 years have struggled to improve survival rates.