Malignant potential of oral lichen planus without epithelial dysplasia: a systematic review and meta-analysis of longitudinal studies
- 1Egas Moniz Center for Interdisciplinary Research, Egas Moniz School of Health & Science
- 2Oral Surgery and Oral Medicine Department, Egas Moniz School of Health & Science
Abstract
Introduction: Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa classified as a potentially malignant oral disease. However, its risk of malignant transformation remains controversial because of heterogeneous diagnostic criteria and methodologies across studies.
Objective: To assess the malignant transformation rate of non-dysplastic OLP through a systematic review and meta-analysis of longitudinal studies.
Materials and methods: A systematic review was conducted according to PRISMA guidelines and registered in PROSPERO (CRD420261295782). PubMed, Embase, and grey literature were searched. Longitudinal observational studies including patients with histopathologically diagnosed OLP, without epithelial dysplasia at diagnosis, and reporting malignant transformation rates were included. The review focused specifically on longitudinal evidence evaluating malignant transformation in patients meeting these eligibility criteria. Methodological quality was assessed using the Newcastle-Ottawa Scale, and meta-analysis was performed using a random-effects model.
Results: Twenty-four studies, comprising 13, 143 patients and 230 cases of malignant transformation, were included. The pooled malignant transformation rate was 1.56% (95% CI: 1.14–2.12%), with substantial heterogeneity (I² = 74.8%). Subgroup analyses showed no significant differences according to study design, geographic region, or diagnostic criteria. Meta-regression identified the male-to-female ratio as a significant moderator, while sample size and follow-up duration had no significant influence. No evidence of publication bias was observed.
Conclusions: The malignant transformation rate of OLP was very low, with a pooled estimate of 1.56%, supporting continued surveillance. Future research should focus on standardized diagnostic approaches and reliable risk stratification models to improve understanding of malignant transformation in OLP and ensure better population representation.
Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261295782 , identifier CRD420261295782.
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BibTeX
@article{domingues2026malignant,
title = {{Malignant potential of oral lichen planus without epithelial dysplasia: a systematic review and meta-analysis of longitudinal studies}},
author = {Carolina Brás Domingues and João Botelho and António Mano Azul and Pedro Ferreira Trancoso},
journal = {Frontiers in Oncology},
year = {2026},
month = oct,
doi = {10.3389/fonc.2026.1949729},
url = {https://www.frontiersin.org/articles/10.3389/fonc.2026.1949729/full},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Malignant potential of oral lichen planus without epithelial dysplasia: a systematic review and meta-analysis of longitudinal studies
AU - Carolina Brás Domingues
AU - João Botelho
AU - António Mano Azul
AU - Pedro Ferreira Trancoso
PY - 2026
DA - 2026/10/13
JO - Frontiers in Oncology
DO - 10.3389/fonc.2026.1949729
UR - https://www.frontiersin.org/articles/10.3389/fonc.2026.1949729/full
AB - Introduction: Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa classified as a potentially malignant oral disease. However, its risk of malignant transformation remains controversial because of heterogeneous diagnostic criteria and methodologies across studies. Objective: To assess the malignant transformation rate of non-dysplastic OLP through a systematic review and meta-analysis of longitudinal studies. Materials and methods: A systematic review was conducted according to PRISMA guidelines and registered in PROSPERO (CRD420261295782). PubMed, Embase, and grey literature were searched. Longitudinal observational studies including patients with histopathologically diagnosed OLP, without epithelial dysplasia at diagnosis, and reporting malignant transformation rates were included. The review focused specifically on longitudinal evidence evaluating malignant transformation in patients meeting these eligibility criteria. Methodological quality was assessed using the Newcastle-Ottawa Scale, and meta-analysis was performed using a random-effects model. Results: Twenty-four studies, comprising 13, 143 patients and 230 cases of malignant transformation, were included. The pooled malignant transformation rate was 1.56% (95% CI: 1.14–2.12%), with substantial heterogeneity (I² = 74.8%). Subgroup analyses showed no significant differences according to study design, geographic region, or diagnostic criteria. Meta-regression identified the male-to-female ratio as a significant moderator, while sample size and follow-up duration had no significant influence. No evidence of publication bias was observed. Conclusions: The malignant transformation rate of OLP was very low, with a pooled estimate of 1.56%, supporting continued surveillance. Future research should focus on standardized diagnostic approaches and reliable risk stratification models to improve understanding of malignant transformation in OLP and ensure better population representation. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/view/CRD420261295782 , identifier CRD420261295782.
SN - 2234-943X
ER -