Metformin may improve the outcomes of patients with GBM when added to current treatment consisting of maximal safe surgical resection followed by neo-adjuvant TMZ and concomitant accelerated hypofractionated limited-margin XRT followed by adjuvant TMZ. Our Neuro-Oncology group at McGill University reviewed the results of an ongoing Phase II study in patients with GBM. A group of 33 patients were treated according to protocol, and with a median follow-up of 11 months, the median survival was 17.5 months which compares favourably to current results from standard treatment with a beneficial 2-week shortening of the XRT treatment time.