Low Incidence of Oral Squamous Cell Carcinoma in Patients With Oral Lichen Planus on Sustained Anti-Inflammatory Therapy: A Single-Centre Retrospective Study of 273 Patients

Background: Oral lichen planus (OLP), a chronic inflammatory disease, can progress to oral squamous cell carcinoma (OSCC). The malignant transformation rate may be lower in OLP patients receiving anti-inflammatory therapy. Objective: To describe cases of malignant transformation among OLP patients on topical/systemic anti-inflammatory therapy. Methods: The medical records of 273 patients with OLP at an academic institution were retrospectively reviewed. Patients with epithelial dysplasia at OLP diagnosis were excluded. Biopsy-confirmed OSCC cases diagnosed >= 6 months after the initial visit were included. Chi-square and t-tests compared categorical and numerical variables, respectively. Results: The mean age at OLP diagnosis was 63 years (standard deviation [SD]: 12.2, range: 19-92); 79.9% were women and 89.4% were White. Most patients had erosive OLP (EOLP) (61.9%). 16.5% had concurrent genital LP and 10.6% had cutaneous LP. Tacrolimus swish-and-spit was the most frequently prescribed treatment (100%), followed by 10 mg clotrimazole troches (89.4%) and topical corticosteroids (85%). The median duration of clinical follow-up was 2.9 years (interquartile range: 1-5.5). Three (1.1%) patients developed OSCC on average 6.3 years post-OLP diagnosis, all with EOLP. OSCC most frequently affected the tongue (66.7%), followed by the gingiva (33.3%). Out of 3 tumours, one was stage II, one was stage III, and one was stage IV. OLP patients with vs. without OSCC were more often male (P = .04) and more frequently experienced dysphagia (P < .001). Conclusion: OSCC incidence was low in OLP patients on sustained anti-inflammatory therapy, occurring exclusively in those with EOLP. Males and patients with dysphagia more often developed OSCC.