Clinical Significance of Ki-67 Staining Index in Acoustic Neurinoma

The correlation between various clinical parameters and MIB-1 (Ki-67) staining indices was evaluated in 58 acoustic neurinomas. The index ranged from 0.37% to 6.61% (mean 1.70%), and did not correlate with age, sex, or initial tumor volume. Sixteen of the 18 tumors removed subtotally or partially showed regrowth, and two showed a volume reduction. The 16 patients with regrowth were divided into two groups according to Ki-67 staining index, < 2.00% and > or = 2.00%. These groups had a significant difference in tumor doubling time (TDT). In addition, there was a significant logarithmic correlation between Ki-67 staining index and TDT. Ki-67 staining index can be used as an index of regrowth rate in partially or subtotally removed acoustic neurinomas. Intraoperative assessment of Ki-67 staining index may be useful for better management planning as well as the estimation of prognosis.