About medulloblastoma

Brain tumors are the second most common malignancy among children less than 20 years of age. Medulloblastoma is the most common malignant brain tumor, comprising 14.5% of newly diagnosed cases.In adults, medulloblastoma is rare, comprising less than 2%; of CNS malignancies.

The incidence of childhood medulloblastoma is higher in males (62%) than females (38%). Medulloblastoma and other PNET tumors are more prevalent in younger children than older children. 40% of medulloblastoma patients are diagnosed before the age of 5, 31% are between the ages of 5 and 9, 18.3% are between the ages of 10 and 14, and 12.7% are between the ages of 15 and 19. [source: Wikipedia]

Common symptoms caused by medulloblastoma

• Loss of balance, trouble walking, worsening handwriting, or slow speech.
• Morning headache or headache that goes away after vomiting.
• Nausea and vomiting (especially in the morning or after a nap).
• Unusual sleepiness or change in energy level.
• Double vision or inability to focus on an object.
• Change in personality or behavior.
• Unexplained weight loss or weight gain.

Risk categories for childhood medulloblastoma

Classifiction for Average Risk assesment may include the following:

• The child is older than 3 years of age
• The tumor is at the very back of the brain
• All of the tumor was removed by surgery or there was a very small amount remainin;
• The cancer has not spread to other parts of the body

Classifiction for High Risk assesment may include the following:

• The child is younger than 3 years of age
• The tumor is not at the very back of the brain
• Some of the tumor was not removed by surgery
• The cancer has spread to other parts of the body

Average Risk Treatment Options

The traditional post-surgical treatment for these patients has been radiation therapy of the whole brain and spine. The minimal dose of radiation therapy needed for disease control is unknown. Attempts to lower the craniospinal radiation dose without chemotherapy have resulted in an increased incidence of isolated leptomeningeal relapse (i.e. tumor spread of a multiplicity of small tumor nodules coating the brain and possibly into the spine). However, the lower radiation dose, when coupled with chemotherapy, has been shown to result in disease control in up to 80% of patients and may decrease the severity of neurocognitive sequelae (or lifelong, irreparable neurological and cognitive effects affecting the quality of the patient’s life.) Long-term survivors who had not reached puberty at the time of diagnosis are at high risk for growth failure, and growth hormone replacement therapy has not been shown to increase the likelihood of disease relapse.

High Risk Treatment Options

In poor-risk patients, the addition of chemotherapy has improved the duration of disease-free survival. These are patients who, at diagnosis, have locally extensive and often unresectable tumor (tumor that cannot be removed by surgery) in the posterior fossa (the rear base of the brain) and/or noncontiguous metastatic disease within or outside of the central nervous system (spread of the tumor to different areas of the body such as into the patient’s bones or spinal cord.) High dose chemotherapy has improved progression-free survival for patients with these high-risk parameters at diagnosis. Such patients should be considered for entry into a clinical trial. The severe toxic effects of the high dose chemotherapy and radiation therapy should be weighed against the likelihood of such treatments achieving the desired result

Treatment Options for Children Younger than 3 Years in Age

Because of the reluctance to use extensive radiation therapy (especially craniospinal radiation therapy) in young children due to concerns about resultant severe neurocognitive deficits, higher than standard doses of chemotherapy has been extensively explored in children younger than 3 years, and in some studies in children younger than 6 years, with medulloblastoma. Different chemotherapeutic regimens have been employed, but the outcome of such treatment has been relatively disappointing, resulting in disease control in only 20% to 30% of patients. In some of the earlier studies, craniospinal and local boost radiation therapy were utilized after completion of chemotherapy or when the children reached 3 years of age. Despite this approach, overall disease control still remained only in the 30% to 35% range. Most of the children who had long-term benefit were those who had non-disseminated, totally resected disease (a tumor that had been completely removed by surgery and prior thereto had not spread to other areas of the brain or into the spinal fluid). In attempts to make chemotherapy even more effective, other highly toxic drugs have been added to these multi-agent approaches, including intravenous and intraventricular methotrexate. In few relatively small studies, in patients who had non-disseminated tumors that were completely resected, 5-year progression-free survival after the addition of methotrexate was approximately 60%. Other relatively smaller scale studies have been completed suggesting improved survival rates in a similar subset of children using higher dose chemotherapy without methotrexate, supported by peripheral stem cell rescue. Given its potential neurotoxicity, methotrexate remains a problematic drug to incorporate in the treatment of children with medulloblastoma. There seems to be a subset of patients who can be effectively treated with chemotherapy alone, and it is likely that the wider availability and application of molecular genetic markers will, in time, better identify this subset.

Recurrence

Recurrence is not uncommon and may develop many years after initial treatment. Disease may recur at the primary tumor site or by cerebrospinal fluid dissemination. Approximately 60% of patients with localized disease at diagnosis will have some component of disseminated disease at relapse, even after radiation therapy to the entire brain and spine. Entry into studies of novel therapeutic approaches including high-dose chemotherapy and autologous stem cell rescue at the time of relapse after radiation therapy alone or radiation therapy and chemotherapy should be considered.