Childhood Cancer Name:
Medulloblastoma, cerebellar PNET
What is Medulloblastoma?
Medulloblastoma Is the most common malignant brain tumor in children, begins when healthy cells in the cerebellum (that controls balance and motor skills), which is the back of the brain change and grow out of control, forming a mass. It is considered malignant because it tends to spread to other parts of the brain and spinal cord.
More than 70% of all medulloblastomas occur in children younger than 10, peak age at presentation is children 3-8 years. It is more common in boys than girls.
Medulloblastomas develop in a part of the brain called the posterior fossa, sometimes can spread to other parts of the brain or spinal cord, through the cerebrospinal fluid (CSF).
- Classic medulloblastoma
- Desmoplastic nodular medulloblastoma
- Large-cell or anaplastic medulloblastoma
- Medulloblastoma with neuroblastic or neuronal differentiation
- Medulloblastoma with glial differentiation
- Melanotic medulloblastoma
The most recent WHO classification of medulloblastoma is as follows:
- Medulloblastoma genetically defined.
- Medulloblastoma, WNT-activated- identified in 10-15 % of patients, usually 10 years old and most commonly found in females.
- Medulloblastoma, SHH-activated and TP53-mutant;
Occurs in children under 3 years old and over 16 years old associated with Gorlin´s syndrome.
- Medulloblastoma, SHH-activated and TP53-wildtype.
- Medulloblastoma, non-WNT/non-SHH.
- Medulloblastoma, group 3- more common in males, often metastasis when diagnosed.
- Medulloblastoma, group 4- 25-40% of the cases, the most common subgroup.
- Medulloblastoma histologically defined.
- Medulloblastoma, classic.
- Medulloblastoma, desmoplastic/nodular.
- Medulloblastoma with extensive nodularity.
- Medulloblastoma, large cell/anaplastic.
Doctors have classified medulloblastoma as either standard or high risk based on biopsy results;
Staging is a measure of how far the tumour has spread beyond its original site. The staging system used for medulloblastoma is:
- M0: No evidence of metastases.
- M1: Tumour cells found in cerebrospinal fluid (lumbar puncture cerebrospinal fluid test).
- M2: Tumour spread beyond original site but still in the brain.
- M3: Tumour deposits (seeds) in the spine that are easily seen on MRI scan.
- M4: Tumour spread to areas outside the central nervous system (brain and spine).
In rare cases, the tumor can be associated with familial syndromes including Gorlin’s syndrome, Turcot’s syndrome, Li-Fraumeni, and Rubenstein-Taybi syndrome.
Childhood Cancer Localization:
Medulloblastoma is located in the cerebellum (the part of the brain that controls movement, balance, and posture).
Childhood Cancer Noticeable Symptoms:
- The most common symptoms are nausea and vomiting (usually in the morning)
- Lethargy, irritability
- Difficulty handwriting or coordinating
- A gradual decline in school work
- Changes in personality
- Abnormal gait
- difficulty speaking
- vision problems
Important: The signs of childhood medulloblastoma vary and often depend on the child’s age and where the tumor is located. In some cases, the tumor can spread to the spinal cord, causing another set of symptoms, such as back pain, an inability to control the bowels and bladder and difficulty walking.
Childhood Cancer Diagnostic Method:
Lumbar puncture, magnetic resonance (MRI), Computed tomography (CT or CAT) scan, biopsy, surgical removal and histological diagnosis.
- Lumbar puncture: to collect cerebrospinal fluid (CSF) from the spinal column, The sample of CSF is checked under a microscope for signs of tumor cells.
Researchers are looking at laboratory tests for tumor samples to identify specific genes, proteins, and other factors unique to Medulloblastoma.
There are some genetic syndromes which are associated with Medulloblastoma:
||Gene (Chromosomal Location)
|Nevoid basal cell carcinoma syndrome (Gorlin’s syndrome)
||PTCH (9q22.3), TSC2 (16p13)
|Turcot’s syndrome A
Unfortunately, a full genetic test to determine the type of medulloblastoma is not yet routinely available. The Pacific Pediatric Neuro-Oncology Consortium (PNOC) conduct clinical trials of new therapies for children with brain tumors with the mission to identify personalized treatment challenges. Here are some examples of the clinical trials all around the U.S that treat medulloblastoma according to the molecular biology of the tumor (more at the end of the chapter):
Childhood Cancer Treatment:
The initial treatment is surgery. However, if the tumor has caused a build-up of cerebrospinal fluid, the surgeon may first need to perform an urgent operation to make SHUNT that helps divert the flow of fluid to the abdomen, to reduce the pressure.
In general, patients need to be checked for increased intracranial pressure, which if present, needs to be controlled either by drugs (steroids) or by neurosurgical drainage (external drainage). Treatments for medulloblastoma are based on the type and stage of the tumor, possible side effects. Treatment includes surgery, radiation therapy, proton therapy and chemotherapy. Current treatment plans tailor treatment recommendations based on the molecular subgroup of medulloblastoma. Gentler therapies could be used for children with a good prognosis while reserving the most intense treatments for those with high-risk tumors.
- Surgery: the removal of the tumor and some surrounding healthy tissue, the goal is to remove as much of the tumor as possible.
- Radiation therapy: reduce radiation therapy to the brain and spinal cord, or higher dose if the tumor was not removed completely.
- Radiation doses can produce declines in memory and intelligence, as well as damage to the hypothalamus and pituitary gland, which produce or direct the production of essential hormones such as growth hormone, thyroid hormone, cortisone, as well as reproductive and sexual hormones.
- In children under three, high dose, chemotherapy may be used to delay or eliminate the need for radiotherapy.
- There is a new modality called Proton beam therapies, a type of radiation treatment that uses protons to spare more tissue that is normal and reduce the risk of many complications and side effects. Learn more about Proton beam therapies here.
- Dana Farber Institute and Massachusetts General Hospital are running a clinical trial (active, not recruiting): Proton Beam Radiation Therapy in Treating Younger Patients with Brain tumors- https://clinicaltrials.gov/ct2/show/NCT00105560
- Proton Therapy Center at MD Anderson also offers this modality for pediatric cancer patients.
- Chemotherapy: After surgery, most children receive chemotherapy to destroy any remaining cancer cells.
In children younger than 3 years of age is usually within a clinical trial and may include the following:
- Surgery followed by chemotherapy to delay radiation therapy.
- Surgery followed by high-dose chemotherapy with stem cell transplant.
- Chemotherapy only.
Important: The treatment for infants with medulloblastoma remains highly problematic. The volumes and doses of radiotherapy required for disease control cause significant brain injury. For this reason, most therapeutic approaches have focused on either delaying or eliminating radiotherapy by the use of increasingly aggressive chemotherapy supported by autologous stem cell transplant.
Follow up, Late effects:
- The younger the child, the more pronounced the toxicity is likely to be.
- After the operation, your child may have difficulties with coordination, weakness in his extremities and problems with balance.
- Because a child’s developing brain is so vulnerable, radiotherapy can cause long-term effects such as problems with growth and development, delayed puberty, cognitive impairment and emotional difficulties.
- Follow up is important, ask your doctor about it.
- The biggest advice is to understand the biology of the tumors and characterizing the tumors base on their molecular and cytogenetic makeup. With this information is possible to get target therapy.
- Children with Medulloblastoma should have their treatment planned by a team of healthcare providers who are experts in treating childhood brain tumors a multidisciplinary team is necessary. The team includes members from neurosurgery, neuro-oncology, neurology, radiation oncology, and stem cell transplantation, as well as psychology/social work, nutrition, physical and occupational therapy, and the school liaison program.
Research, clinical trials: