Risk of Malignant Transformation in 3173 Subjects with Histopathologically Confirmed Oral Lichen Planus: A 33-Year Cohort Study in Northern Italy

SIMPLE SUMMARY: Up to 1–4% of OLP patients could develop oral cancer, and identifying factors that could help in early detection could be extremely useful. The aim of our cohort study was to assess the clinical characteristics of one of the biggest populations ever reported with a histologically confirmed diagnosis of OLP. We identified that OLP patients who developed oral cancer usually underwent less frequent periodical follow-up visits, and older age increased the risk of death. As a significant number of OLP patients have a risk of malignant transformation, there is a critical need to review these patients preferentially, by trained clinicians, at least once a year, possibly for a lifetime. ABSTRACT: Background: Oral lichen planus (OLP) is considered an oral potentially malignant disorder. The aim of our study was to estimate the risk for oral cancer in patients diagnosed with OLP. Methods: A population-based cohort study between January 1988 and December 2020 at one hospital in Northern Italy was performed. The primary endpoint of the study was that of the histopathological diagnosis of oral cancer during the follow-up period. Results: The study population comprised 3173 patients. During the follow-up period, 32 men and 50 women developed an oral squamous cell carcinoma (2.58%), with a mean time of 103.61 months after the initial diagnosis of OLP, and 21 patients died because of oral cancer. Almost half of the deceased patients had the last follow-up visit before cancer diagnosis in a period of more than 12 months. Older age, having a red form of OLP and fewer sites of involvement, increased the risk of having cancer, while age and no treatment increased the risk of death. Conclusion: This is the largest group of OLP patients with such a long follow up ever reported. Due to the increased risk of having a malignant transformation, especially in elderly subjects, OLP patients should be regularly followed up, particularly in the Northern Italian population.