Low Ki‐67 proliferation index is an indicator of poor prognosis in gastric cancer

Abstract

We designed this study to assess the biologic significance of Ki-67 proliferation index (PI) in gastric cancer. Gastric cancer tissue from 245 patients were immunostained for Ki-67. Ki-67 PI was defined as the percentage of tumor cells positive for Ki-67. In addition, we have previously evaluated the expressions of nine epithelial mesenchymal transition (EMT)-related proteins. The relationship between Ki-67 PI and clinicopathologic parameters, patient survival, and EMT data were sought. Low Ki-67 PI was correlated with poorly differentiated histology (P = 0.034), an advanced T stage (P < 0.001), and lymph node metastasis (P = 0.011). Also, the low PI group was found to have a significantly worse prognosis than the high PI group (P = 0.003, log-rank test). Multivariate analysis revealed that Ki-67 PI remained as an independent prognostic factor (hazard ratio (95% CI) = 0.670 (0.450-0.999)). Furthermore, greater expressional changes of EMT-related proteins were found to be significantly associated with low Ki-67 PI (P = 0.025). These findings suggest that Ki-67 PI is an effective tool for predicting survival in gastric cancer. In addition, we found that an invasive property presented as EMT-related protein expressional changes was inversely correlated with a proliferative activity in gastric cancer.