RADIOTHERAPY FOR ATYPICAL OR MALIGNANT INTRACRANIAL MENINGIOMA

Purpose: To study the natural history of intracranial atypical and mal ignant meningiomas, and the role of radiotherapy in the treatment of t hese tumors. Methods and materials: The records of the 59 patients who were treated at the Princess Margaret Hospital between 1966 and 1990 with histologically confirmed intracranial atypical or malignant menin giomas were retrospectively reviewed. The median age was 58 years. Twe nty-four patients were referred for radiation immediately after diagno sis and the remainder after at least one recurrence. The extent of the most recent surgery prior to radiation was gross total excision in 17 , subtotal excision in 35, biopsy in 3, and none or unknown in 4, Seve nteen had atypical meningiomas, defined as the presence of mitoses, nu clear atypia, or necrosis. Forty-two had malignant meningiomas on the basis of brain invasion (60%) or a pathologist's designation of malign ant or hemangiopericytic meningioma. All patients received megavoltage radiation to a median dose of 50 Gy. Results: Disease progressed in 3 9 patients (66%) after radiation. Of these, 36 died of meningioma and 3 were alive after further surgery. The 5-year actuarial overall and c ause-specific survivals were 28 and 34%, respectively. Age less than 5 8, treatment after 1975, and a radiation dose of 50 Gy or more were in dependently associated with higher cause-specific survival by multivar iate analysis. Conclusions: Young age, modern imaging and treatment pl anning techniques, and a postoperative radiation dose of at least 50 G y contribute to improved outcome in patients with atypical or malignan t meningiomas. We recommend that all patients receive radiotherapy imm ediately after initial surgery.