Radiation Therapy in Treating Patients Who Have Undergone Surgery for Newly Diagnosed Grade II or Grade III Meningioma

DISEASE CHARACTERISTICS: * Histologically confirmed newly diagnosed meningioma, including the following subtypes: * Atypical WHO grade II meningioma greater than or equal to 4 mitosis per high-power field \[HPF\] or the presence of at least 3 of the following variables: * Cellularity * Architectural sheeting (i.e., patternless pattern) * Macronuclei cell formation * Small cell formation * Malignant WHO grade III meningioma * All locations allowed except for optic nerve sheets tumors * Complete or subtotal resection as assessed by the surgeon after verification with a postoperative MRI and according to Simpson guidelines * No neurofibromatosis type 2 (NF-2) PATIENT CHARACTERISTICS: * WHO performance status 0-2 * Not pregnant or nursing * Fertile patients must use effective contraception during study therapy * May be registered on this trial only once * No clinical evidence of second malignancies except carcinoma in situ of the cervix or basocellular carcinoma * No psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule PRIOR CONCURRENT THERAPY: * No prior radiotherapy to the brain or meninges interfering with the protocol treatment plan