Oligodendroglioma.

Before treatment can be initiated, an accurate histopathologic diagnosis must be made. There is still some controversy regarding histologic criteria for the diagnosis of oligodendroglioma and which grading system is best. Molecular diagnosis is becoming an important adjunct to traditional histopathologic diagnosis. For low-grade oligodendrogliomas, maximal surgical resection should be attempted if technically feasible. Radiation therapy or chemotherapy should be deferred unless the patient has significant neurologic symptoms or growth of tumor. Aggressive or anaplastic tumors should also be treated with maximal surgical resection. Increasingly, chemotherapy is replacing radiation therapy as the initial postoperative treatment, with radiation therapy being either delayed until after completion of chemotherapy or, in select patients, deferred until recurrence.