A drug used with surgery and radiation therapy to treat malignant glioma that is high grade and has not already been treated. It is also used with surgery to treat glioblastoma multiforme that has recurred (come back). Gliadel Wafer is a form of carmustine contained in a wafer. The wafer has a coating that dissolves slowly and releases carmustine directly into the area where the brain tumor was removed. This form may have fewer side effects and work better than other forms of carmustine. Gliadel Wafer is a type of alkylating agent. Also called carmustine implant and polifeprosan 20 carmustine implant.