Observation or Radiation Therapy in Treating Patients With Grade I, Grade II, or Grade III Meningioma

Inclusion Criteria: 1. A histologically documented World Health Organization (WHO) grade I, II, or III meningioma, newly diagnosed or recurrent, and of any resection extent, confirmed by central pathology review. Patients are partitioned according to three groupings: Group I (low risk), Group II (intermediate risk), and Group III (high risk) as defined below: * Group I (low risk): Patients with a newly diagnosed WHO grade I meningioma that has been gross totally resected (Simpson's grade I, II, or III resections, with no residual nodular enhancement on postoperative imaging) or subtotally resected (residual nodular enhancement or Simpson grade IV or V excision). The extent of resection will be based upon the neurosurgeons' assessment and postoperative MR imaging. * Group II (intermediate risk): Patients with a newly diagnosed gross totally resected WHO grade II meningioma or patients with a recurrent WHO grade I meningioma irrespective of the resection extent. Resection extent will be recorded on the same basis described above for the low-risk group. * Group III (high risk): Patients with a newly diagnosed or a recurrent WHO grade III meningioma of any resection extent; patients with a recurrent WHO grade II meningioma of any resection extent; or patients with a newly diagnosed subtotally resected WHO grade II meningioma. In the setting of a newly diagnosed meningioma, the histologic diagnosis must have been reached within 6 months of Step 2 registration. Resection extent will be recorded on the same basis described above for the low-risk group. * 1.1 In the setting of a newly diagnosed meningioma, the histologic diagnosis must have been reached within 24 weeks prior to Step 2 registration. In the setting of a recurrent meningioma, there are no such time constraints. Additional resection or biopsy is encouraged for patients with recurrence but is not requisite. If further biopsy or resection is performed at recurrence, these specimens must be submitted; submission of the original pathology specimens is encouraged but not required. The diagnosis of recurrence solely on the basis of imaging findings is permitted, but if no additional resection is performed, specimens from prior resection must be submitted. * 1.2 In cases of newly diagnosed or surgically treated recurrent meningioma, the operating neurosurgeon must provide a Simpson grade for the degree of resection. 2. History/physical examination, including neurologic examination, within 8 weeks prior to Step 2 registration 3. Zubrod Performance Status 0-1 4. Age ≥ 18 5. All patients must have a magnetic resonance imaging (MRI) scan within 12 weeks prior to Step 2 registration. Both preoperative and postoperative MRIs are required for all newly diagnosed patients in groups I, II, or III. In the setting of group II or III patients with recurrent/progressive meningioma and without recent surgery, a pre-operative study may not apply, although MRI documentation of recurrence or progression is required. MRIs must include precontrast T1, T2, and flair images and multiplanar (axial, sagittal, and coronal) postcontrast T1. The postoperative study must be completed within 12 weeks of surgery. * 5.1 Group I: All group I patients will have surgery. Preoperative and postoperative MRIs are thus required in order to assess resection extent. * 5.2 Group II: Surgery will be undertaken for the subgroup with a gross totally resected WHO grade II meningioma. For these patients preoperative and postoperative MRIs are necessitated. For the other subgroup with recurrent WHO grade I meningioma, preoperative and postoperative MRIs are required if surgery is undertaken for the recurrent/progressive tumor. However, only the follow-up imaging documenting recurrence or progression will apply if further surgery is not completed. * 5.3 Group III: Surgery will be undertaken for the subgroup with a newly diagnosed WHO grade III meningioma. For these patients preoperative and postoperative MRIs are obligatory. For the subgroups with recurrent WHO grade II or III meningioma, preoperative and postoperative MRIs are required if surgery is undertaken for the recurrent/progressive tumor. However, only the follow-up imaging documenting recurrence or progression will apply if further surgery is not completed. 6. For woman of childbearing potential who are intermediate or high risk: * 6.1 Negative serum pregnancy test within 14 days prior to Step 2 registration * 6.2 The patient must agree to practice adequate contraception from the time of the negative serum pregnancy test throughout the entire course of EBRT. 7. Patient must sign study-specific informed consent prior to study entry Exclusion Criteria: 1. Extracranial meningioma 2. Multiple meningiomas 3. Hemangiopericytoma 4. Major medical illnesses or psychiatric impairments which, in the investigators opinion, will prevent administration or completion of the protocol therapy or preclude informed consent 5. Previous radiation therapy to the scalp, cranium, brain, or skull base 6. Prior invasive malignancy (except non-melanomatous skin cancer) unless disease free for a minimum of 3 years (for example, carcinoma in situ of the breast, oral cavity, or cervix are all permissible) 7. Patients with severe, active comorbidity including, but not restricted to: * 7.1 Unstable angina and/or congestive heart failure requiring hospitalization at the time of Step 2 registration * 7.2 Transmural myocardial infarction within the last 6 months * 7.3 Acute bacterial or fungal infection requiring intravenous antibiotics at the time of Step 2 registration * 7.4 Chronic obstructive pulmonary disease exacerbation or other respiratory illness requiring hospitalization or precluding study therapy at the time of Step 2 registration * 7.5 Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects. Note, however, that laboratory tests for liver function and coagulation parameters are not required for entry into this protocol. * 7.6 Acquired immune deficiency syndrome (AIDS) based upon current Centers for Disease Control and Prevention (CDC) definition; note, however, that HIV testing is not required for entry into this protocol. The need to exclude patients with AIDS from this protocol is necessary because the treatments involved in this protocol may be significantly immunosuppressive. * 7.7 Active connective tissue disorders such as lupus or scleroderma if the patient is intermediate or high risk 8. Inability to receive gadolinium