Is 50 Gy Sufficient to Achieve Long-Term Local Control after Incomplete Resection of Typical Neurocytomas?

Abstract

Central neurocytomas are generally described as rare benign central nervous system tumors. They can be divided in two groups, typical and atypical neurocytomas. Typical neurocytomas are associated with better outcome. This study investigates whether a decrease in radiation dose from 54 Gy to 50 Gy for incompletely resected typical neurocytomas would jeopardize the outcome. The data of all reported neurocytoma patients were reviewed. Tumors with an atypical histology or an MIB-1 labeling index > 3% were defined as atypical neurocytomas and excluded from this analysis. If the reported data were incomplete, the authors were contacted for additional relevant data. Two groups were created based on an EQD2 (equivalent dose in 2-Gy fractions) of < or = 50 Gy or > 50 Gy and compared for overall survival and local control. Additionally, the patients who received an EQD2 < 50 Gy were compared to those patients receiving an EQD2 = 50 Gy. The data were complete in 94 patients. The 10-year survival was 100% after < or = 50 Gy (n = 34) and 93% after > 50 Gy (n = 60; p = 0.51). The 10-year local control rates were 83% and 88%, respectively (p = 0.69). At 10 years, overall survival was 100% both after < 50 Gy and after 50 Gy (p = 1.0), local control was 71% and 90%, respectively (p = 0.029). After incomplete resection of typical neurocytomas, radiotherapy with 50 Gy (2-Gy fractions) appears sufficient, as it resulted in similar local control as doses > 50 Gy and insignificantly better local control than doses < 50 Gy.