Medical Health Encyclopedia

Grade IV.

Primitive neuroecto-dermal tumor (PNET). Composed of malignant forms of early, undeveloped nerve cells called neuroblasts. (This malignancy is also referred to as neuroblastoma.)

Very rare, but more common in children. Primitive nerve cells that grow very rapidly. Usually occur in cerebellum.

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Surgery followed by radiotherapy to brain and spinal cord. Chemotherapy in young children. Investigative high-dose chemotherapy with stem cell rescue for children with relapsed cancer.

Common Brain Tumors: Oligodendrogliomas

DESCRIPTION OF OLIGODENDROGLIOMAS: They develop from oligodendrocyte glial cells. These cells form the protective coatings around nerve cells. Pure cell types are rare. Most often occur in mixed gliomas. Categorized as either low- or high-grade. Most are low grade II.

Description of Grade

Usual Treatment

Low Grade: Low grade difficult to tell from astrocytomas, although they are usually calcified. Very likely to bleed. Usually spread along nerve pathways of the brain and spine and rarely outside this area. In spite of difficulty in removing surgically, in some patients survival can be 30 to 40 years. Usually have better prognosis than astrocytomas of equal grade. Occur mostly in middle-aged adults, although there is also a small peak of incidence in children.

Treatment usually delayed until progression causes symptoms.

Surgery to remove whole tumor. Radiotherapy often follows in all adults over 40 or in anyone in which tumor cannot be completely removed. Solid evidence is lacking on this approach, however, and there is some debate on its benefits.

Trials using chemotherapy after radiation are promising. Two-thirds of patients respond to PCV (combination of procarbazine, lomustine and vincristine.) Sustained remissions averaging 16 years often achieved. Pure oligodendrogliomas respond better than mixed gliomas. Temozolomide is showing promise as second-line treatment. Others under investigation.