Medulloblastoma is the most common kind of cancerous brain tumor in children under age 16. It's typically found between ages 3 and 8. About 500 children in the U.S. are diagnosed with a medulloblastoma each year. They're more common in boys than in girls, and they happen less often in adults.
These tumors start near the base of the skull -- in the cerebellum. This is the part of the brain that controls balance and motor skills. The tumors tend to grow quickly and can spread to other parts of the brain, spinal cord, and bone marrow.
Doctors don't know why these tumors appear, but people with some conditions, including Li-Fraumeni syndrome and Gorlin syndrome, are more likely to get them. In rare cases, they can be passed from parents to their children.
Some of the first symptoms include:
- Behavioral problems
- Changes in handwriting
- Clumsiness or other balance problems
- Nausea or vomiting in the morning
- Tilting the head to one side
- Vision problems
Once the medulloblastoma has spread to the spinal cord, you also might notice:
If your child has symptoms, his pediatrician will want to do a few tests to find out what's going on. These may include a physical exam and a neurological exam, which checks reflexes, senses, and muscle strength among other things. The doctor also may recommend the following:
- MRI (magnetic resonance imaging): This uses powerful magnets and radio waves to make detailed pictures of the inside of your child's brain and spine.
- CT scan (computerized tomography): An X-ray machine takes detailed pictures of your child's brain from different angles.
- PET scan (positron emission tomography): Radiation is used to make 3-dimensional color images so the doctor can find the cancer cells.
Your child's treatment will depend on whether the cancer has spread. The doctor probably will recommend one or more of the following:
- Surgery: This is usually the first step. The goal is to cut out as much of the cancer as possible without affecting nearby areas of the brain. Your child's doctor will also take a small piece of the tumor (called a biopsy) to confirm that it's cancer.
- Chemotherapy: The doctor will likely suggest this after surgery to destroy any remaining cancer cells. It's given through an IV or with pills.
- Radiation therapy: This is also used to kill cancer cells. It uses high-energy X-rays or other types of radiation. It also can slow the growth of tumors the doctor couldn't remove during surgery.
- Proton therapy: A low dose of radiation is sent directly to the tumor. This is more precise than radiation therapy and can prevent damage to healthy tissue and organs.
About 70% to 80% of children who are treated for an average-risk tumor (one that isn't difficult for doctors to get to) are free of cancer five years after their diagnosis.