Medulloblastoma

Name: Medulloblastoma.

Childhood Cancer Name: Medulloblastoma, cerebellar PNET.

Main types:

  • Classic medulloblastoma
  • Desmoplastic nodular medulloblastoma
  • Large-cell or anaplastic medulloblastoma
  • Medulloblastoma with neuroblastic or neuronal differentiation
  • Medulloblastoma with glial differentiation
  • Medullomyoblastoma
  • Melanotic medulloblastoma

Special cases: 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: Headaches, nausea or vomiting (usually in the morning), difficulty coordinating or writing, difficulty speaking, vision problems.

Childhood Cancer Diagnostic method: Magnetic resonance, surgical resection, and histological diagnosis.

Childhood Cancer Treatment:  Surgery, chemotherapy, radiation therapy, proton therapy.

 

What is a 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.

Characteristics:  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.

Biology:  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).

Signs and Symptoms:

  • The most common symptoms are nausea and vomiting.
  • Lethargy, irritability
  • Headaches
  • Clumsiness
  • Difficulty handwriting
  • A gradual decline in school work
  • Changes in personality
  • Abnormal gait 

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.

 

Diagnosis: Lumbar puncture, magnetic resonance (MRI), Computed tomography (CT or CAT) scan, biopsy, surgical removal.

  • 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.

Parent´s tip: 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.

 

Genetic counseling:

There are some genetic syndromes are associated with Medulloblastoma,

Disease 
Gene (Chromosomal Location) 
Li-Fraumeni syndrome  
p53 (17p13.1)
Nevoid basal cell carcinoma syndrome (Gorlin's syndrome)  
PTCH (9q22.3), TSC2 (16p13)
Turcot's syndrome A  
APC (5q21–q22)
Rubenstein-Taybi syndrome  
CBP (16p13.3)

 

Researchers are looking at laboratory tests for tumor samples to identify specific genes, proteins, and other factors unique to medulloblastoma.
It is now known that medulloblastoma is made up of 4 subtypes:

  • WNT medulloblastoma: identified in 10-15 % of patients, usually 10 years old and most commonly found in females.
  • SHH medulloblastoma: Occurs in children under 3 years old and over 16 years old associated with Gorlin´s syndrome.
  • Group 3 medulloblastoma: more common in males, often metastasis when diagnosed.
  • Group 4 medulloblastoma: 25-40% of the cases, the most common subgroup.

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. Read more about it here.

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):

 

The stages: Doctors have classified medulloblastoma as either standard or high risk based on biopsy results.

The most recent WHO classification of medulloblastoma is as follows :

  • Medulloblastoma, genetically defined.
    • Medulloblastoma, WNT-activated.
    • Medulloblastoma, SHH-activated and TP53-mutant.
    • Medulloblastoma, SHH-activated and TP53-wildtype.
    • Medulloblastoma, non-WNT/non-SHH.
      • Medulloblastoma, group 3.
      • Medulloblastoma, group 4.
  • Medulloblastoma, histologically defined.
    • Medulloblastoma, classic.
    • Medulloblastoma, desmoplastic/nodular.
    • Medulloblastoma with extensive nodularity.
    • Medulloblastoma, large cell/anaplastic.

 

Treatment:  Initially, 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, 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.

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.

Parent´s tip: 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.

 

Types of 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.

 

Chemotherapy followed by conformal radiation therapy.

  • 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 normal tissue 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: Proton Beam Radiation Therapy in Treating Younger Patients with Brain Tumors https://www.cancer.gov/about-cancer/treatment/clinical-trials/search/v?id=NCI-2011-00201&r=1
    • 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.

 

Here are some tools that can help you explain your child about brain cancer treatments.

 Testimonials: 

Experts: 

 

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 really important, ask your doctor about it.

 

Links for more information:

 

Research, clinical trials:

  

References: