Fractionated radiosurgery will be delivered to atypical meningioma lesions in salvage setting for patients who present post-surgical residual lesion or develop recurrence.

Meningioma is the most common intracranial tumor (1). World Health Organization (WHO) grade II (atypical) meningioma recurs more frequently than WHO grade I (benign) meningioma, and patients with subtotally resected atypical meningioma should be treated with adjuvant radiation therapy (2). However, many atypical meningiomas can be gross totally resected, and whether to administer radiation to this population remains unclear. Apart from extent of resection, clinical characteristics such as age and gender and tumor-related characteristics such as tumor size and location have poor predictive capacity to determine which lesions will recur.

The lack of professional consensus on the role of adjuvant radiation therapy (RT) derived from the heterogeneity and retrospective nature of the published data: standard fractionation fails to demonstrate a benefit in term of local control and survival.

Recent advances in radiotherapy technology (staged radiosurgery) give the possibility to reach high dose levels only in tumor volume and in the same time to save the surrounding healthy tissues.

The purpose of this study is to verify the related toxicity of a new radiotherapy protocol and as second end point to evaluate the efficacy on disease local control at 3 years.

Inclusion Criteria:

• Patients had residual or recurrent atypical meningioma (grade II) after surgery (Simpson score)
• Age: ≥ 18 years old
• Karnofsky performance Status ( KPS) ≥ 70
• Written consent

Exclusion Criteria:

• Pregnancy
• Neurofibromatosis type 2 (NF2)
• Concomitant aggressive haematological or solid neoplasm