The role of KI67 as a marker in the diagnose and grading evaluation of oral potentially malignant disorder and oral squamous cell carcinoma: a systematic review

Ki67 is one of the preferred markers to provide standardization in the diagnosis/grading of oral potentially malignant disorder (OPMD) and oral squamous cell carcinoma (OSCC) in histopathological examinations. The aim of this systematic review is to evaluate the methodologies, findings and interpretations of Ki67 expression studies used in histopathological examinations for the diagnosis and grading of oral epithelial dysplasia (OED), OPMD (oral lichen planus, oral leukoplakia, erythroplakia, oral submucous fibrosis, and oral epithelial dysplasia) and OSCC cases in the literature. Articles in the Web of Science, Pubmed and Scopus databases within the last 5 years (2020-2024) were searched with the related keywords. The modified Quality in Prognosis Studies (QUIPS) tool was used to assess the "risk of bias" of the articles included. 50 articles were included in the systematic review. General risk of bias assessment of the articles included in the review, it was determined that the studies were high risk in terms of selection bias and performance bias, medium risk in terms of detection bias, and low risk in terms of attrition bias and reporting bias. Although it is generally possible to distinguish NM & OED with Ki67 expression, it may be more challenging than comparing NM & OSCC. Ki67 expression is not considered successful in determining the metastatic and recurrence potential of OSCC and OPMD. Ki67 expression may be lower in oral submucous fibrosis (OSMF) than in other types of OPMD, and the most important reason for this may be the proliferative activity change characterized by the typical atrophic epithelium of OSMF.