Treatment of Medulloblastoma
After diagnosis, treatment for medulloblastoma typically involves an assessment of surgical options. This is both to improve the diagnosis but also to remove either all or the tumor in an attempt to improve prognosis.
Secondary treatments may involve radiation therapy or chemotherapy to treat any remaining tumor that may have either spread to the spine or other parts of the brain or that tissue that was unable to be removed. Recent advances in radiation treatments may also provide a more focused treatment option to avoid ancillary damage to other parts of the brain. Treatment with chemotherapy is designed to kill remaining cells left behind or those that may have spread to other areas of the spine or brain. Typically, children and adults with medulloblastoma receive these drugs as an injection into the vein (intravenous chemotherapy). Chemotherapy may be recommended in some cases during radiation treatment. Certain high dose chemotherapy may also be followed by stem cell rescue (a stem cell transplant using the patient's own stem cells). Chemotherapy treatments may either be conventional or part of a clinical trial. Clinical trials enroll eligible participants to study the effectiveness of new treatments or to study new ways of using existing treatments. These studies provide a chance to try the latest treatment options, though the risk of side effects may not be known. Your doctor may recommend other treatment options or combinatorial treatments depending on the specific type of tumor and/or the location of the tumor.
Care and recommendations of treatment are typically recommended by a neuro-oncologist. It is recommended that you seek treatment by a qualified-neuro-oncologist and when considering critical treatment options, he or she should welcome and/or be able to assist with second opinions from another neuro-oncologist or institution.
Your neurosurgeon will be able to discuss how feasible surgery is for treatment. The goal of surgery is to remove all of the visible tumor(s), however there may be cases where this is not possible depending on the where the main tumor is located. If there is any tumor left over after surgery, your doctors may need to intensify radiation or chemotherapy.
Surgery to remove the tumor may cause damage to the brain which may be permanent or may be temporary. This occurs in approximately 25% of patients and can lead to language difficulties and emotional concerns. While surgical resection can improve overall prognosis in some cases surgery alone will not cure medulloblastoma.
Radiation is administered by a specialist called a radiation oncologist. Radiation is a cancer treatment that uses high-energy X rays or other types of radiation to kill cancer cells. It was first noted in the 1950s that patients who received radiation to their brain and their spine had higher survival rates compared to patients who did not receive radiation.
Medulloblastoma can spread to the covering of the brain and spinal cord – that is why patients get radiation to the tumor bed (where their tumor was before surgery) as well as the rest of the brain and the entire spinal cord.
The most common type of radiation is called external-beam radiation therapy. It is radiation that comes from a machine outside the body. Your radiation therapy schedule consists of a specific number of treatments given over a set period of time (usually 5-7 weeks). A type of radiation therapy that may be used for Medulloblastoma is called proton therapy.
Proton Beam Therapy
Proton beam therapy is a specific type of radiation therapy that uses proton particles for treatment rather than the photons (x-rays) that are used for most radiotherapy. Protons have an anti-tumor effect that is very similar to conventional photon radiotherapy. In some brain tumors, protons are superior to photon radiation because they can spare nearby normal brain tissue from potentially harmful effects of radiation.
Radiation Side Effects
Radiation therapy often causes inflammation in the brain, which can temporarily make symptoms worse. Steroids are used to control inflammation when necessary.
In children older than 3–5 years of age, the current convention for radiotherapy involves radiation to the entire craniospinal axis in order to treat or provide prophylaxis against metastatic recurrence.
Because the radiation of the whole brain in young children is associated with a decline in neurocognitive function, patients under the age of 3-5 years of age are treated with chemotherapy-only regimens.
Chemotherapy is the use of drugs to destroy tumor cells by keeping the tumor cells from growing, dividing, and making more cells. Chemotherapy for medulloblastoma is usually given into a vein. The majority of patients need a central line or a port to make giving chemotherapy easier and more convenient. Chemotherapy regimens usually consists of a defined number of cycles given over a set period of time. Patients may receive one drug at a time or a combination of different drugs given at the same time.
Despite such aggressive multi-modal therapy, approximately 30% of patients eventually succumb to this disease, and survivors cope with the long-term side effects of treatment that have significant impacts on their quality of life.
Chemotherapy Side Effects
Side effects of chemotherapy depend on the individual patient, the type of chemotherapy as well as the dose. General side effects include fatigue, risk of infection, nausea and vomiting, hair loss, and decreased appetite. These side effects tend to go away after treatment is complete. Talking with your child’s oncologist about the chemotherapy regimen and the side effects is highly encouraged.
The Future of Medulloblastoma Treatment
Recent advancements in the understanding of medulloblastoma cell of origin and subtypes may lead to the development of new models of this disease, particularly group 3 and group 4. Understanding of the cell of origin may aid in driving key genetic aberrations in the appropriate cell type and developmental context in preclinical models. Attempting to model medulloblastoma subtypes, rather than subgroups, may provide the opportunity to model important driver events that are common in a particular subtype but rare at a subgroup level. Development of these preclinical models may improve the likelihood of new trial development.