Medulloblastoma

Medulloblastoma is a type of brain cancer. It most often affects children. But in rare cases, it can happen in adults. These tumors start in the cerebellum, near the back of the brain. The cerebellum controls balance and coordination.

Any tumor in the brain may press against a part of your brain and cause problems.  

Medulloblastoma is a primary brain tumor. That means it starts in brain cells. It hasn't spread to the brain from somewhere else in the body. This type of tumor may spread (metastasize) within the brain and spinal cord. In rare cases it can spread to the bone marrow, lungs, or other parts of the body. The outlook for tumors that have spread tends to be worse than for tumors that stay in one place.

These are fairly fast-growing tumors. They are grouped into four molecular subtypes, but this classification is evolving:

• WNT. This is the least common subtype. The cancer cells have mutations of CTNNB1 encoding b-catenin.
• SHH (sonic hedgehog). These cells have SHH receptor PTCH mutations or SHH inhibitor SUFU mutations. GLI1 and GLI2 amplifications are also possible.
• Group 3. The cells have MYC amplification and gene expression of photorecepto/GABAergic.
• Group 4. This is the most common sub-group. CDK6 and MYCN are amplified. Neuronal/glutamatergic gene expression is seen.

Talk with your provider if you'd like to learn more about the subgroup you or your child are in and what the genetics mean for your treatment and outlook.

A small number of people with medulloblastoma also have certain inherited disorders. These disorders increase their risk of getting these tumors, as well as other types of cancer.

These disorders include:

• Gorlin syndrome.
• Turcot syndrome.
• Cowden syndrome.
• Gardner syndrome.
• Li-Fraumeni syndrome.

But many people who get medulloblastoma don't have one of these inherited disorders. It's unclear what causes most of these tumors.

Medulloblastoma is more common in children and young adults. In a few people with this condition, there's a link to an inherited disorder. But in most people, there's no known inherited risk. Researchers are actively trying to understand the genetics of medulloblastoma in hopes of better understanding the risk and possible treatments. The risk for medulloblastoma is higher in:

• Children.
• People with certain inherited genetic disorders, such as those listed above.
• Young adults.

Symptoms of medulloblastoma may start slowly and get worse as the tumor grows. Headaches are common. Sometimes a brain tumor may block the normal flow of cerebral spinal fluid (CSF), leading to increased intracranial pressure. This may cause headache, nausea, vomiting, and dizziness. Because the tumor is often in the cerebellum, it may affect balance and coordination early on.

Some of the general symptoms of medulloblastoma include:

• Balance problems or clumsiness.
• Changes in thinking ability.
• Dizziness.
• Double vision or other eye problems.
• Tiredness and lack of energy (fatigue).
• Headaches.
• Nausea and vomiting.
• Hearing loss.
• Irritability and changed behavior.

Doctors usually take a complete health history. They will also ask about recent symptoms and past health conditions, including a family health history. A complete physical exam will be done, including a nervous system exam. Your doctor may ask you (or your child) to do simple things like walk, touch your finger to your nose, hold your hands out, or follow a light with your eyes. If a doctor thinks you may have a brain tumor, imaging tests of the brain will be needed, such as:

• MRI scan of the brain and spinal cord. MRIs use radio waves, magnets, and a computer to make detailed images of the inside of your body. For this test, you lie still on a table as it passes through a long, tube-like scanner. If you're not comfortable in small spaces, you may be given a sedative before the test. A contrast dye may be injected into your blood for this test. It helps outline the structures in your head so they show up more clearly on the scans.
• Spinal tap (lumbar puncture). To do this, a very thin needle is put through the space between the bones of your lower spine and slid into the space around your spinal cord. A small amount of the fluid there (called the CSF or cerebrospinal fluid) is then removed to check it for tumor cells.

You may first see your primary healthcare provider. He or she may refer you to a doctor that deals with brain disorders. This can include a:

• Neurologist. This specialist diagnoses and treats brain and spinal cord diseases.
• Neurosurgeon. This is a specialist who does brain or spinal cord surgery.
• Neuro-oncologist. This is a specialist in brain and spinal cord cancers.

Depending on the type and location of the tumor, your healthcare team will decide the best treatment plan for you (or your child). In general, the main treatment in adults is surgery to remove as much of the cancer as possible. This both removes the tumor and provides a tissue sample for testing. Fully removing the tumor increases the chances of a good outcome. After surgery, you may also have radiation therapy and, in some cases, chemotherapy as well. Depending on the tumor characteristics, you may have 1 or more of the following treatments:

• Surgery to remove as much of the tumor as possible (often the main treatment).
• Radiation therapy to the brain and spinal cord, including where the tumor was.
• Chemotherapy, in addition to surgery and radiation.

If your intracranial pressure is high, you may need to have a tube called a shunt inserted. Surgery is done to place the shunt so that it drains away the excess fluid. This lowers the intracranial pressure. Follow-up MRI scans will be done regularly to watch your condition.

You will work with your medical team to decide on the best treatment plan for you.

Many people with medulloblastoma typically have good outcomes. Some people have complications due to the surgery or other treatments. In some cases, the tumor comes back (recurs) after treatment. To check for recurrence, you'll likely need follow-up MRI scans in the weeks after surgery and then a few times a year after that. One possible complication is posterior fossa syndrome. This a form of short-term (temporary) brain damage, due to surgery. Symptoms may include problems with language, emotions, and movement. This may last for weeks or years.

Other complications can include:

• Nausea, vomiting, and fatigue, due to radiation therapy or chemotherapy.
• Recurrent tumor.
• Side effects of radiation, such as infertility or cognitive changes.

Talk with your doctor about the risk of treatment complications (both short- and long-term), your overall outlook (prognosis), and the chances of the tumor returning.