Correlation between Ki-67 index and some clinical aspects of acoustic neuromas (vestibular schwannomas)

Evaluation of the proliferation activity of neuromas has a practical meanin g when there are doubts about the complete resection of the tumor. Evaluati on of the clinical aspects connected with increased proliferation activity may have a much broader application. The aim of this study was to correlate selected clinical and radiologic aspects of vestibular schwannomas with th e results of the Ki-67 index. The studied group included 23 males and 20 fe males; Unilateral neuromas were stated in 38 cases (mean age, 52.2 years) a nd bilateral tumors in 5 cases (mean age, 44.2 years). The immunohistochemi cal tests (Ki-67) were performed on the specimens preserved in formalin and stored in paraffin. The Ki-67 index was estimated in a semiquantitative st udy. The mean value of Ki-67 index was 1.86%. In case of unilateral neuroma s (n = 38), the average Ki-67 index was 1.74%. in 5 cases of bilateral tumo rs, the index amounted to 2.79% (P = 0.278). No significant correlation was found by comparing the value of the Ki-67 index with the age of patients ( P = 0.410: r = 0.128). Significant differences in the value of the Ki-67 in dex were noted in the subgroups of tumors that were evaluated radiologicall y as growing and stable. The mean value of Ki-67 index was 3.17% in the fir st subgroup; in stable neuromas, it was significantly lower, amounting to 1 .11% (P = 0.020). Such results may confirm that the growth rate of vestibul ar schwannomas varies and may explain the difficulties in estimating the gr owth of neuromas on the basis of clinical aspects only.