DNA Aneuploidy and Abnormal DNA Ploidy Status as Predictors of Malignant Transformation in Oral Leukoplakia: A Narrative Review

Background: Oral leukoplakia is a clinically important oral potentially malignant disorder with variable risk of progression to oral squamous cell carcinoma. Histopathological grading of oral epithelial dysplasia remains the primary method for risk assessment; however, its predictive accuracy is limited by sampling variability, lesion heterogeneity, and interobserver variation. DNA aneuploidy and abnormal DNA ploidy status have therefore been investigated as objective biomarkers of genomic instability and potential predictors of malignant transformation. Aim: This narrative review evaluates whether DNA aneuploidy or abnormal DNA ploidy status predicts malignant transformation of oral leukoplakia to oral squamous cell carcinoma compared with diploid DNA status, and whether DNA ploidy should be interpreted as a stand-alone prognostic marker or as part of combined risk-assessment models. Materials and Methods: A structured PubMed/MEDLINE search (last performed on 12 July 2026) identified 162 records using terms related to oral leukoplakia, oral potentially malignant disorders, DNA ploidy, DNA aneuploidy, cytometry, malignant transformation, and oral squamous cell carcinoma. After screening and full-text eligibility assessment, 45 studies were included and organised according to their evidential role as core prognostic studies, PVL-specific subgroup evidence, and supporting/background evidence addressing diagnostic relevance, dysplasia correlation, treatment monitoring, genomic instability, and methodological development. Results: Most core prognostic studies showed that DNA aneuploidy, abnormal DNA content, or chromosomal instability was associated with increased malignant transformation risk compared with diploid or non-aneuploid status. Several studies reported higher transformation rates, hazard ratios, or improved prediction when DNA ploidy was combined with dysplasia grading, lesion site, clinical heterogeneity, or other biomarkers. However, predictive performance varied across studies, and DNA ploidy alone often showed modest sensitivity, specificity, or positive predictive value. Diploid or non-aneuploid status appeared more useful for identifying lower-risk lesions, although it did not completely exclude malignant transformation. PVL evidence suggested frequent aneuploidy and aggressive genomic behaviour, but DNA ploidy appeared less reliable for discriminating risk within PVL. Conclusions: DNA aneuploidy and abnormal DNA ploidy status are meaningful markers of genomic instability and are associated with increased malignant transformation risk in oral leukoplakia. However, when used alone, DNA ploidy often shows only modest predictive performance, and prediction improves consistently when it is combined with dysplasia grading and other clinicopathological factors. Their strongest clinical value is therefore as adjunctive biomarkers within combined clinicopathological and molecular risk models, rather than as stand-alone replacements for histopathological assessment; routine clinical implementation is not yet supported by the current evidence.