Medulloblastoma

A medulloblastoma is a type of primitive neuroectodermal tumour (PNET). PNETs develop from primitive nerve cells (called neuroectodermal cells). Medulloblastomas commonly occur in the back of the brain, in the cerebellum. Medulloblastomas are fast-growing, high-grade tumours.

Medulloblastoma can often spread through the cerebrospinal fluid (CSF) to other parts of the central nervous system.

Recurrent medulloblastomas are tumours that have come back after treatment.

Medulloblastoma may be divided into groups based on molecular genetic analysis. Prognosis and treatment may vary depending on the group.

Medulloblastomas may be staged based on your age, whether the tumour has spread to other parts of the brain or into the CSF and if the tumour is able to be completely removed with surgery. The stage of the tumour determines the treatment that is most appropriate.

A medulloblastoma is average risk if the child is over 3 years old, all or most of the tumour can be removed with surgery and the tumour has not spread to other parts of the brain or into the CSF.

A medulloblastoma is high risk if the child is under 3 years old, the tumour can’t be completely removed with surgery and the tumour has spread to other parts of the brain or into the CSF.

Treatment of medulloblastomas depends on:

• the size and location of the tumour
• whether the cancer has spread
• the child’s age, neurological condition and general health
• whether the tumour is average risk or high risk

Surgery is usually the first treatment used. The goal of surgery is to remove as much of the tumour as possible. In many cases, surgeons can remove the entire tumour. Surgery may also be used to relieve a buildup of CSF (hydrocephalus).

Radiation therapy is often given after surgery. Even if the tumour was completely removed, the entire brain and spinal cord are usually treated with low-dose radiation (called craniospinal radiation) because medulloblastomas have a high tendency to spread to these areas. A higher-dose boost of radiation is given to the area from where the tumour was removed. Doctors try to avoid giving radiation to children under 3 years old because it can damage developing brain cells. In these cases, doctors will give chemotherapy first and then give radiation when the child is older.

Chemotherapy can also be used to treat medulloblastomas. Chemotherapy is usually given during and after radiation therapy. In children under 3 years old, chemotherapy is given to try to delay radiation therapy. Chemotherapy may also be given directly into the CSF (called intrathecal or intraventricular chemotherapy). High-dose methotrexate is usually used for intrathecal or intraventricular chemotherapy.

Chemotherapy drug combinations commonly used include:

• cisplatin (Platinol AQ), lomustine (CeeNu, CCNU) and vincristine (Oncovin)
• cisplatin, cyclophosphamide (Cytoxan, Procytox) and vincristine
• cyclophosphamide, etoposide (Vepesid, VP-16), cisplatin and vincristine

High-dose chemotherapy followed with stem cell transplant may also be used to treat medulloblastoma.

Risk of the tumour coming back is highest in the first 2 years after treatment. Treatment of recurrent medulloblastomas depends on:

• whether the tumour comes back in the original site or in a different area of the brain
• the type of treatment that was given for the original tumour

Surgery may be used if the tumour comes back in the same area and has not spread.

If the child previously had radiation therapy, then radiation therapy is usually not used. However, in some cases a boost of radiation therapy may be given.

Other treatments used for recurrent medulloblastomas include chemotherapy, high-dose chemotherapy with stem cell transplant and targeted therapy.

Many children with medulloblastomas are treated in a clinical trial. Clinical trials look at new ways to prevent, find and treat cancer. Find out more about clinical trials.