Rate of malignant transformation of Oral Lichen Planus: a systematic review

OBJECTIVE: The aim of this study is to systematically review the literature to determine: 1) the malignant transformation rate (TR) of Oral Lichen Planus (OLP) and its risk factors; 2) whether or not Oral Lichenoid Lesions (OLL) have a different malignant TR. MATERIALS AND METHODS: PubMed, Scopus and Web of Science were used as search engines: only observational, full-length, English language studies were investigated. PRISMA protocol was used to evaluate and present results. PROSPERO registration code is CRD42016048529. RESULTS: Among 7429 records screened, only 21 were included in this review. Ninety-two out of 6559 patients developed Oral Squamous Cell Carcinoma (OSCC), with an overall TR of 1.40% (1.37% for OLP and 2.43% for OLL), an annual TR of 0.20%. Female gender, red clinical forms and tongue site seem to slightly increase the transformation risk. CONCLUSIONS: This systematic review confirms that both OLP and OLL, the latter with a slightly higher TR, may be considered Potentially Malignant Disorders (PMDs) and suggests that erosive type, female gender and tongue site should be considered as risk factors for OLP transformation. Major efforts should be done to establish strict clinical and histological criteria to diagnose OLP and to perform sounder methodological observational studies. This article is protected by copyright. All rights reserved.