Architectural dysplasia in surgical margins and the risk of local relapse in oral cancer

Background: A major challenge in the clinical management of oral cavity squamous cell carcinoma is local relapse. Even when surgical margins are tumor-free, local relapses occur frequently, and relapse prediction by histology remains suboptimal. In leukoplakia, an oral potentially malignant disorder, the presence of architectural dysplasia is a critical risk factor for malignant transformation. This study aimed to investigate whether the presence of architectural dysplasia in oral cavity squamous cell carcinoma surgical margins is a risk factor for local relapse. Methods: Hematoxylin and eosin-stained slides of resection margins from a consecutive cohort of surgically treated patients diagnosed with stage I–IV oral cavity squamous cell carcinoma between 2008 and 2014 were assessed for the presence of architectural dysplasia (N = 311). Five-year local relapse-free survival rates of oral cavity squamous cell carcinoma with architectural dysplasia were compared to those of oral cavity squamous cell carcinoma without architectural dysplasia. Results: In total, 92 of 311 (29.6%) of oral cavity squamous cell carcinoma displayed architectural dysplasia in the margins. The presence of architectural dysplasia was associated with higher patient age, female sex, less pack years, lower cT-stage, and a cohesive tumor growth pattern. In oral cavity squamous cell carcinomas with architectural dysplasia, postoperative (chemo)radiotherapy was less often indicated compared with oral cavity squamous cell carcinoma without architectural dysplasia (19.5% vs. 36.1%, p = 0.009). Five-year local relapse-free survival was significantly lower in oral cavity squamous cell carcinoma with architectural dysplasia than in oral cavity squamous cell carcinoma without architectural dysplasia (83.1% vs. 94.9%, p = 0.017). Conclusions: Oral cavity squamous cell carcinoma arising in the background of architectural dysplasia displays relatively favorable clinical and histopathological characteristics. Nonetheless, the presence of architectural dysplasia in oral cavity squamous cell carcinoma surgical margins is associated with a higher risk of local relapse, indicating its clinical relevance.