gliadel is an FDA - approved drug - a wafer containing a concentrated amount of a chemotherapy agent. These wafers are placed into the brain cavity after the tumor is resected (removed) and deliver a steady amount of immediate chemotherapy medicine to the surrounding brain tissue. Also, since Gliadel is a local chemotherapy, it will prevent the detrimental suppression (weakening) of the immune system shown with systemic (throughout the body) chemotherapy.