Timing of Malignant Transformation in Recurrent Versus Nonrecurrent Oral Potentially Malignant Disorders: A Retrospective Study

OBJECTIVE: Postoperative recurrence of oral potentially malignant disorders (OPMDs) is common. This study investigated whether the timing of malignant transformation differs between recurrent and nonrecurrent lesions. METHODS: This retrospective observational study included patients who underwent carbon dioxide laser excision for OPMDs and later developed oral squamous cell carcinoma between July 2002 and July 2024. Clinicopathological characteristics and transformation intervals were compared between recurrent and nonrecurrent lesions. RESULTS: Among 898 treated patients, 38 (4.2%) developed malignant transformation. Of these, 28 (73.7%) had no postoperative recurrence before malignant transformation, whereas 10 (26.3%) experienced recurrence. Although most malignant transformation cases occurred in nonrecurrent lesions, recurrent lesions had a significantly shorter transformation interval (p = 0.014). All recurrent lesions progressed to oral squamous cell carcinoma within 2.3 years, whereas nonrecurrent lesions exhibited a broader range of transformation intervals, extending from several weeks to more than 13 years. No significant differences were observed in other clinicopathological characteristics. CONCLUSIONS: Although most malignant transformation cases occurred in OPMDs without documented postoperative recurrence, recurrent OPMDs were associated with a significantly shorter transformation interval. These findings suggest that recurrent lesions may warrant closer clinical surveillance, while long-term surveillance remains important regardless of recurrence status.