An Evidence-Based Update on the Potential for Malignancy of Oral Lichen Planus and Related Conditions: A Systematic Review and Meta-Analysis

Simple Summary Lichen planus (LP) is a chronic inflammatory mucocutaneous disease of autoimmune nature and unknown etiology, which can affect the oral mucosa, skin, nails, scalp, genitalia, and other mucous membranes. The anatomical location most frequently affected by LP is the oral cavity-called oral lichen planus (OLP)-where white reticular lesions may also be accompanied by erosive, atrophic, bullous, papular, or plaque lesions. The most important feature of OLP is its capacity to develop into oral cancer throughout the course of the disease, which is why OLP is currently recognized as an oral potentially malignant disorder (OPMD). New primary-level studies (n = 20; 11,512 patients suffering from OLP or related lesions) have been published in the last 5 years on this topic. In the present meta-analysis, we provide an updated OLP malignant transformation ratio, which is higher than what was previously reported; resolve some remaining controversies; and provide new recommendations for clinical practice in the management of OLP patients.Abstract A systematic review and a meta-analysis is presented on published articles on the malignant transformation of oral lichen planus (OLP) and related conditions, which, based on current evidence, updates an earlier systematic review published by our research group that included publications until November 2018. In this updated study (Nov-2023) we searched MEDLINE, Embase, Web of Science, and Scopus. We evaluated the methodological quality of studies (QUIPS tool) and carried out meta-analyses. The inclusion criteria were met by 101 studies (38,083 patients), of which, 20 new primary-level studies (11,512 patients) were published in the last 5 years and were added to our updated study. The pooled malignant transformation ratio was 1.43% (95% CI = 1.09-1.80) for OLP; 1.38% (95% CI = 0.16-3.38) for oral lichenoid lesions; 1.20% (95% CI = 0.00-4.25) for lichenoid reactions; and 5.13% (95% CI = 1.90-9.43) for OLP with dysplasia. No significant differences were found between the OLL or LR groups and the OLP subgroup (p = 0.853 and p = 0.328, respectively), and the malignant transformation was significantly higher for the OLP with dysplasia group in comparison with the OLP group (p = 0.001). The factors that had a significant impact with a higher risk of malignant transformation were the presence of epithelial dysplasia, a higher methodological quality, the consumption of tobacco and alcohol, the location of lesions on the tongue, the presence of atrophic and erosive lesions, and infection by the hepatitis C virus. In conclusion, OLP behaves as an oral potentially malignant disorder (OPMD), whose malignancy ratio is probably underestimated as a consequence essentially of the use of inadequate diagnostic criteria and the low methodological quality of the studies on the subject.