Research shows the benefits of using cannabidiol (a non-psychoactive component of cannabis) in the treatment of glioblastoma:

… The control group received temozolomide (chemotherapy) only and had a 44% 1-year survival rate. In contrast, the cannabidiol combination plus temozolomide group showed a 83% 1-year survival rate with a median survival over 662 days compared with 369 days in the control group…

Read the full article: Cannabinoids in Glioblastoma Therapy: New Applications for Old Drugs.

Another article can be found here: The Antitumor Activity of Plant-Derived Non-Psychoactive Cannabinoids