Medulloblastoma

Medulloblastomas are tumors that arise in the posterior fossa region of the brain (near the brain stem and cerebellum, the part of the brain responsible for movement). The exact cell of origin is not known. Tumors that have the same characteristics can also arise in other parts of the brain. This tumor type has a tendency to spread to other areas of the brain and spinal cord.

Medulloblastoma accounts for about 20 percent of childhood brain tumors. They most often occur in the first decade of life; half occur in children younger than 5 to 6 years of age. These tumors are slightly more common in males than in females. Most patients have a history of headache and morning vomiting, which gets worse with time. Because of the tumor’s location, patients may also have clumsiness and problems with tasks like handwriting. It is rare, but some patients can have visual loss at diagnosis. And if the tumor has spread to the spinal cord, symptoms may include back pain, difficulty walking and inability to control bladder and bowel functions.

Survival ranges from 60 to 80 percent. Surgery, radiation therapy and chemotherapy are used to treat medulloblastoma. The aim of surgery is to remove as much tumor as possible. When surgery is done by highly skilled neurosurgeons using modern techniques, most tumors can be totally removed. After surgery, tests are performed to see if there is any residual tumor at the operated site and if and where the tumor has spread. Patients with totally resected tumors that have not spread are now treated with reduced-dose radiation to the brain and spinal cord. The goal is to decrease the long-term side effects of radiation. Then patients receive chemotherapy. In a national study, 80 percent of children treated in this way survived. If the tumor has spread to other areas of the brain and spinal cord (or in rare cases, to the bone marrow) the patient is considered high-risk. These patients receive higher-dose radiation therapy before chemotherapy.