Salvage Radiosurgery for Recurrent Supratentorial Primitive Neuroectodermal Tumors: A Single Institutional Series and Review of the Literature

Introduction: Supratentorial primitive neuroectodermal tumor is a rare, aggressive intrinsic brain tumor with limited treatment options for recurrent disease. SRS as a treatment modality in the recurrent setting was investigated. Methods: A retrospective review of 8 patients treated with SRS for local or distant recurrence of supratentorial PNET from 1999 to 2014 was conducted. Results: Thirty-six tumors were treated in 15 sessions in 8 patients. The median patient age was 22.5 (interquartile range [IQR], 14.75-43.5 years) with a median 21-month period from diagnosis until SRS (IQR, 16-23.75 months). The median prescription isodose volume was 1.85 cm3 (IQR, 1.85-7.02 cm3); median tumor margin dose was 18 Gy (IQR 14-20 Gy); and median isocenters was 2 (range 1-13). No patients experienced adverse radiation effects. All but 1 patient died, and the median overall survival was 32 months (IQR, 26.75-53.5 months) with median overall survival following SRS of 9.5 months (IQR, 5.25-30 months). Univariate analysis failed to demonstrate a statistically significant association between age, number of gamma knife treatments, interval to gamma knife, and margin radiation dose with overall survival. Discussion/Conclusion: This series supports the use of SRS in patients with recurrent supratentorial PNET following multimodal therapy.