RATIONALE: Sometimes a tumor may not need treatment until it progresses. In this case, observation may be sufficient. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor, such as 3-dimensional conformal radiation therapy and intensity-modulated radiation therapy, may kill more tumor cells and cause less damage to normal tissue. It is not yet known whether observation is more effective than radiation therapy in treating patients with meningioma.

PURPOSE: This phase II trial is studying observation to see how well it works compared with radiation therapy in treating patients with grade I, grade II, or grade III meningioma.