For patients with a rare brain tumor known as craniopharyngioma, the treatment options are slim — and often hazardous. Although the tumor is usually not aggressive, its location is perilous. Growing at the base of the skull near the pituitary gland, the tumor compresses parts of the brain as it enlarges, causing vision and learning problems and endocrine dysfunction, as well as morbid obesity. There is currently no drug to shrink the tumor, so the only options are surgical removal and radiation, which can leave patients with serious, lasting problems.