Surgery
Surgery is the most common treatment for a child with medulloblastoma. Depending on the location of the tumor, a child's doctor may remove as much of it as possible by creating an opening in the skull in an operation called a craniotomy. Since the macroscopic appearance of the tumor may lead to a false diagnosis, in every case a portion of the tumor has to be secured for histological examination. Usually, a large portion of the tumor is situated in the lumen of the fourth ventricle, and the removal of this part of the tumor restores free cerebrospinal fluid passage.
Radiation Therapy
Postoperative radiation therapy has changed both qualitatively and quantitatively over the years. Since medulloblastomas are extraordinarily sensitive to irradiation, postoperative radiation treatment should be performed in every case. Primary x-ray therapy solely on the basis of the clinical diagnosis of a possible medulloblastoma is not recommended for various reasons. There is statistical proof of the fact that the tumor may as well be a benign spongioblastoma of the cerebellum (cerebellar astrocytoma), which can be removed by operation and permanently cured. Furthermore, without prior release of pressure in the infratentorial region a reactive swelling of the tumor may cause a most dangerous additional increase in intracranial pressure during radiation. Moreover, primary radiation treatment may result in the loss of valuable time during which the increase in intracranial pressure may lead to irreversible damage of the optic nerves, which soon results in blindness. Re-establishment of the free cerebrospinal fluid passages, on the other hand, relives the symptoms of brain pressure most quickly and effectively.
With patients surviving longer and in larger numbers, the adverse effects of radiation are becoming better known and recognized. These adverse effects include growth retardation, scoliosis, endocrine dysfunction, and poor school performance. The poor school performance and scoliosis are the most troublesome since these complications are the least amenable to any form of therapy.
Chemotherapy
Chemotherapy is a systemic treatment; drugs flow through the bloodstream to nearly every part of the body to kill cancerous cells Some multicenter studies have demonstrated a slight advantage to those patients who received chemotherapy in addition to standard surgery and radiation therapy. While the differences in survival are not large, the improved results have led to the use of innovative chemotherapy approaches.
Numerous chemotherapeutic agents used either individually or in combination have been tried for treatment of recurrent disease. At present, most authors recommend chemotherapy for children with recurrent medulloblastoma.
Results and Prognosis
Children in whom a diagnosis of medulloblastoma has been established almost invariably show excellent immediate response to radiation therapy and, unless there has been much damage to adjacent brain tissue by the tumor or the surgery, can return to normal activity for varying lengths of time. Long-term survivors, considering the virulence of the neoplasm, are correspondingly frequent. However, long survival does not promise cure. Because medulloblastoma is aggressive, regardless of the extent of the operation and the intensity of the radiation treatment, frequent monitoring is essential. Imaging is the primary mode of monitoring residual disease. MRI should be repeated every 3 months in the first year; every 4 months in the second year; every 6 months in the following 3 years; and yearly thereafter.
