Treatment of atypical neurocytomas.

Background: The majority of central neurocytomas are benign. Approximately 25% of these rare central nervous system tumors are more aggressive, with an MIB-1 labeling index > 2% or atypical histologic features, and are classified as atypical neurocytomas. The objective of this analysis was to define the optimal treatment for patients with these atypical tumors.

Methods: The first atypical neurocytoma was described in 1989. The patients reported since then were reviewed for age, gender, extent of resection, MIB-1 index, histology, irradiation, local control, and survival. In addition to the data available in the literature, more relevant data were obtained from the authors of that literature. Treatment approaches included complete resection alone (CR), complete resection followed by radiotherapy (CR-RT), incomplete resection alone (IR), and incomplete resection followed by radiotherapy (IR-RT). These four therapies were compared for local control and survival using Kaplan-Meier analysis and the log-rank test.

Results: Complete data were available on 85 patients (15 patients who underwent CR, 13 patients who underwent CR-RT, 17 patients who underwent IR, and 40 patients who received IR-RT). Local control rates at 3 years and 5 years were 73% and 57% after CR, 81% and 53% after CR-RT, 21% and 7% after IR, and 85% and 70% after IR-RT, respectively (P < 0.0001). Survival rates at 3 years and 5 years and were 93% and 93% after CR, 90% and 90% after CR-RT, 65% and 43% after IR, and 87% and 78% after IR-RT, respectively (P = 0.0076).

Conclusions: Patients who underwent CR achieved better local control and survival rates compared with patients who underwent IR. After IR, patients appeared to benefit from RT. A beneficial effect of RT after CR was not observed.