Analysis of Ki-67 expression in oral squamous cell carcinoma: Why Ki-67 is not a prognostic indicator

SummaryObjectives: To analyze the prognostic value of Ki-67 in oral cancer and its relationship with Ki-67 expression in precancerous epithelium. Material and methods: We studied 79 tumors from 65 patients. Immunohistochemistry study with Mib-1 monoclonal antibody was used to detect Ki-67 expression in tumor tissue and adjacent non-tumor tissue. The influence of different variables on survival was studied with univariate and multivariate analyses. Results: Ki-67 expression was significantly higher in well-differentiated versus poorly-differentiated carcinomas. The survival time of these patients was affected by the clinical presentation, T, N, stage, and surgical treatment. Ki-67 expression had no impact on survival. An association was found between the parabasal expression of Ki-67 in adjacent non-tumor epithelium and Ki-67 expression in the tumor. Conclusions: Ki-67 lacks prognostic value, probably because it is a marker of the total fraction of proliferating cells, corresponding not only to cells in constant proliferation but also to proliferating cells destined for terminal differentiation.