What is the Prognostic Significance of Ki-67 Positivity in Oral Squamous Cell Carcinoma?

BACKGROUD Numerous studies have stated that Ki-67 is a good prognostic marker in oral squamous cell carcinoma (OSCC). However, some researchers believe the contrary. To address this controversy, we performed a systematic literature retrieval to estimate the prognostic significance of Ki-67 expression in patients with OSCC. METHODS Databases covering Pubmed, Ovid, Web of Science, Embase and the Cochrane library were searched regardless of publication year. Overall survival (OS), local recurrence (LR) and disease-free survival (DFS) were the main outcome measures. Relative risks (RRs) and its 95% confidential intervals (CIs) were used for statistical analysis. RESULTS Twenty-seven articles with 2146 patients were included in this study. The results of the meta-analysis suggested that the pooled RRs and its CIs for OS, LR, and DFS were 1.45 (1.15 - 1.84), 1.76 (0.74 - 4.16) and 1.52 (1.07 - 2.14), respectively. However, the heterogeneities of OS and LR were obvious (I-squared (OS) = 59.4%, I-squared (LR) = 72.6%). After subgroup analysis based on systemic treatment, the cut-off value of Ki-67 expression, ethnicity and types of antibody, the heterogeneities became acceptable. It was observed that systemic treatment, cut-off values of Ki-67 expression, ethnicity and the types of antibody affected the results. The statistical analyses of subgroups suggested that non-systemic treatment, (OR=1.77, 95% CI = 1.39-2.25, p = 0.000) and Asian populations (OR=2.09, 95% CI = 1.32-3.32, p = 0.002) are high risks for Ki-67 high expression, and low cut-off value of Ki-67 expression (OR = 1.44, 95% CI = 1.001-2.072), MIB-1 antibody (OR = 1.48, OR 95% = 1.10-1.99) might affect the identification of results. CONCLUSIONS According to this meta-analysis, high Ki-67 expression might be a negative prognostic marker of patients with OSCC, especially in Asian populations. In addition, Ki-67 expression affects the treatment response.