Stereotactic radiosurgery for WHO II and III meningiomas: analysis of long-term clinical and radiographic outcomes

WHO grade II and III meningiomas are challenging tumors to treat, and the role of stereotactic radiosurgery (SRS) in their treatment is not well defined. We evaluate our experience to better define its role and assess for clinical and radiographic predictors of failure.This is a retrospective analysis of all patients with histological diagnosis of WHO II or III meningioma. Thirteen patients were included. The mean dose to the periphery was 16 Gy (12-20), the mean maximum dose was 31 Gy (13-40), and the mean isodose line was 49% (35-50).The median age was 48 years. The median follow up was 50 months (7-67). All cases had undergone at least one previous resection, and six patients had undergone external beam radiation (EBRT). The median pre SRS Karnofsky performance score (KPS) was 90. The progression free survival (PFS) was 92% and 31% at 1 and 4 years, respectively. Eleven patients required further treatment after SRS. The final tumor volume was decreased in 7 patients, stable in 1, and increased in 6.WHO grade II and III meningiomas are aggressive tumors that will require multiple treatments. SRS may be a useful as an adjuvant treatment or for recurrence.