Should severe epithelial dysplasia be treated?

OBJECTIVE: To identify clinical features associated with progression of primary severe epithelial dysplasia into invasive squamous cell carcinoma (SCC). DESIGN: Longitudinal population-based study. SETTING: Oral dysplasia clinics. PATIENTS: This study involved 118 patients with 118 severe dysplasia who were prospectively enrolled between 1996 and 2014, and the lesions were either completely removed surgically (treated) or actively followed (untreated). MEASUREMENTS: Demographics, habits, clinical information and outcome were compared between the treated and untreated groups. RESULTS: Of the 118 lesions, 77 were treated and 41 were not. The treated lesions showed significantly less progression when compared to the untreated: 5/77 (6%) treated lesions progressed into invasive SCC versus 12/41 (29%) untreated (P=0.004). The 5-year probability (confidence interval) of progression into SCC for the treated was 7.6 (1-14) as compared to 38.6 (16-55) for the untreated. Interestingly the clinical changes at the site of the disease also had strong predictive value for cancer progression. If the site showed no lesion after treatment or after incisional biopsy (40 cases), only 1 (3%) progressed into cancer. If the site showed ever disappearance of the lesion or marked decrease in the size of the lesion to ⩽10mm (29 cases), 4 (15%) progressed. If the site showed lesions with fluctuation in size or persistent in size or marked increase in size (25 cases), 18 (58%) progressed (P<0.001). CONCLUSION: Treatment significantly reduced cancer progression, and phenotypic changes at the site of the disease had significant predictive value for cancer progression.