Tumor Budding and Poor Prognosis in Oral Cancer: A Systematic Review and Meta-Analysis.

BACKGROUND: Tumor budding (TB) has been investigated in several types of solid tumors. In oral cancer, studies show its association with survival. However, for its implementation in routine histological analyses, results with a high certainty of evidence are needed. Therefore, the aim of this systematic review is to explore the association between tumor budding and overall survival (OS), disease-specific survival (DSS), and disease-free survival (DFS) in oral cancer. METHODS: A search was performed in Embase, PubMed, Scopus, Livivo, Web of Science, and Google Scholar. We adopted the following inclusion criteria: studies that evaluate tumor budding in oral cancer, that investigate survival, and presenting cohort design. We excluded reviews and studies without hazard-ratio (HR) data. RESULTS: This systematic review included 22 studies and showed an association between TB and survival. High-grade TB is associated with a worse OS in univariate analysis (HR = 3.11; 95% CI: 2.06-4.69, p<0.01) and multivariate analysis (HR = 2.62; 95% CI: 1.64-4.20, p<0.01); with a poorer DSS in univariate (HR = 2.43; 95% CI: 1.94-3.03, p<0.01) and multivariate analysis (HR = 2.01; 95% CI: 1.43-2.83, p< 0.01); and with a worse DFS in univariate (HR = 1.94; 95% CI: 1.44-2.62, p<0.01) and multivariate analysis (HR = 2.15; 95% CI: 1.31-3.53, p< 0.01). Sensitivity analysis showed that the results are robust, and no significant publication bias was identified in univariate analysis for DFS (Egger's test: p = 0.94). The certainty of the evidence was graded as low or very low. CONCLUSION: Our findings indicate that TB is an independent prognostic factor of OS, DSS, and DFS in oral cancer. However, further studies are needed to increase the certainty of the evidence.