Prognostic significance of Ki67 (MIB1) proliferation index and p53 over-expression in chondrosarcomas

To investigate the prognostic significance of the Ki67 (MIBI)-proliferation index and p53 over-expression in chondrosarcomas, we retrospectively analyzed a cohort of 29 patients with chondrosarcomas using immunohistochemical assays with MIBI and p53 monoclonal antibodies on formalin-fixed, paraffinembedded tissue samples with microwave preparation. We also assessed 19 patients with benign cartilaginous tumors as a control group. There was a significant positive correlation between MIBI index and tumor grade in chondrosarcomas, while there was no significant difference in the MIBI index between the grade-1 chondrosarcomas and the benign cartilaginous tumors. Patients categorized in the high-MIBI-index group had a significantly lower survival rate than those in the low-index group. Moreover, in analyzing the sub-set of the patients with grade-II chondrosarcomas, it was found that they could be prognostically sub-divided according to MIBI index. The p53 index also significantly correlated with patient survival, and there was significant correlation between the MIBI index and the p53 index. However, in multivariate analysis, only the MIBI index and tumor grade proved to be independent prognostic indicators of chondrosarcomas. These results demonstrate that the MIBI index can be a useful procedure for assessing tumor grade in chondrosarcomas, especially for determining the prognosis of patients with grade-II chondrosarcoma.