MIB-1 labeling index predicts recurrence in intraventricular central neurocytomas

Despite the relatively low-grade of most central neurocytomas (CN), evidence suggests the existence of an aggressive subset with a propensity for recurrence. Recent studies have found the MIB-1 labeling index to be a prognostic indicator in CN. Here we review our experience with CN to analyze the relationships between extent of resection, adjuvant therapy, tumor histology, and clinical outcomes based on aggressive histology, as defined by MIB-1 labeling. A retrospective review was performed on histologically proven CN surgically resected from 1993 to 2009 at the University of California at San Francisco. Recurrence rates were analyzed using the Kaplan-Meier method with respect to MIB-1 labeling and extent of resection. All MIB-1 labeling indices were analyzed. A total of 18 patients were identified with a mean age of 30 years (range 17-58 years) and median follow-up of 40 months (5-173 months). The treatments were: gross total resection (GTR) alone (17% of patients), subtotal resection (STR) alone (50% of patients), STR plus radiotherapy (XRT: external beam or stereotactic radiosurgery: 28% of patients), or STR plus chemotherapy (5% of patients). The extent of resection and a MIB-1 labeling index >4% was predictive of recurrence (p<0.01). In the 33% of the patients in whom the tumor recurred, all had STR with MIB-1 labeling >4% with median time to recurrence of 23.5 months. The 2-year and 4-year recurrence rates in patients with MIB-1 labeling >4% were 50% and 75% respectively. No patient with a MIB-1 labeling index <4% who received STR alone had a recurrence. Thus, in patients with CN who were treated with STR, histology demonstrating a MIB-1 labeling index >4% can be a clinically useful prognostic indicator and can help guide adjuvant treatment.