Comparing Radiation After Surgery to Observation After Surgery in Patients With Clinical Low-Risk, Molecular High-Risk Meningioma, and Evaluating Observation After Surgery in Patients With Clinical and Molecular Low-Risk Meningioma

This phase III trial compares post-surgical surveillance to post-surgical radiation therapy for improving survival without disease progression in clinically low-risk patients with a grade 1 meningioma that is new or that has come back after a period of improvement (recurrent) or a new grade 2 meningioma who have undergone surgery. Post-surgical surveillance involves closely watching a patient's condition but not giving treatment unless there are changes in test results. Active surveillance avoids problems that may be caused by treatments such as radiation or surgery. It is used to find early signs that the condition is getting worse. During active surveillance, patients will be given certain exams and tests done on a regular schedule. Radiation therapy uses high energy x-rays, particles, or radioactive seeds to kill cancer cells and shrink tumors. The usual approach for low grade and low clinical risk meningiomas is surgery followed by radiation or no further treatment (observation) based on clinical risk factors such as tumor grade and the amount of tumor able to be removed. Clinical factors such as meningioma grade and the amount of meningioma that was removed help doctors decide whether radiation or observation is better after surgery. In this study, a patient's molecular risk, as determined using biomarkers, is also considered when assigning treatment. For patients with grade 1 or 2 meningiomas with a low clinical risk but high molecular risk of growing or coming back after surgery, this study will compare the usual approach of post-surgery observation to another usual approach of post-surgery radiation. Using high molecular risk to decide usual treatment and receiving the usual radiation could increase the amount of time without the tumor growing or coming back, but it could also cause side effects. For patients with grade 1 or 2 meningiomas with a low clinical risk and low molecular risk of growing or coming back after surgery, this study will evaluate if using molecular risk shows a greater benefit of the usual post-surgery observation.