Inclusion Criteria:

• • Participants must have either:
• • histologically confirmed atypical meningioma, WHO grade II, Simpson grade 4-5 that has been either subtotally resected or biopsied.

OR

• • histologically confirmed malignant/anaplastic meningioma, WHO grade III with any prior surgery.

In the case of recurrent radiographically gross disease, pathologic diagnosis may be from time of original biopsy and/or surgery. Pathology should be reviewed and confirmed at the Participating Institution.

Patients may or may not have neurofibromatosis type 1 or 2.

• • Age 18 years or older.
• • ECOG performance status ≤ 2 (Karnofsky Performance Status ≥ 60, see Appendix A)
• • The effects of proton radiation therapy on the developing human fetus are known to be teratogenic. For this reason, women of child-bearing potential and all men must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while she or her partner is participating in this study, she should inform her treating physician immediately. Men treated or enrolled on this protocol must also agree to use adequate contraception prior to the study, for the duration of study participation, and 4 months after completion of proton therapy.
• • Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

• • Participants may not be receiving any other investigational agents.
• • Participants may not have received prior cranial irradiation.
• • Uncontrolled intercurrent illness including, but not limited to ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements.
• • Pregnant or lactating women are excluded from this study because radiation is known to have teratogenic or abortifacient effects. Because there is an unknown but potential risk of adverse events in nursing infants secondary to treatment of the mother with radiation therapy, breastfeeding should be discontinued if the mother is treated with radiation therapy.
• • Individuals with a history of a different malignancy are ineligible except for the following circumstances. Individuals with a history of other malignancies are eligible if they have been disease-free for at least 3 years and are deemed by the investigator to be at low risk for recurrence of that malignancy. Individuals with the following cancers are eligible if diagnosed and treated within the past 3 years: cervical cancer in situ, and basal cell or squamous cell carcinoma of the skin.