Impact of Postoperative Radiotherapy on the Prognosis of Early-Stage (pT1-2N0M0) Oral Tongue Squamous Cell Carcinoma

PURPOSE To identify subgroups of patients with early-stage (pT1-2N0M0) oral tongue squamous cell carcinoma (OTSCC) who may benefit from postoperative radiotherapy (PORT). PATIENTS AND METHODS This retrospective cohort study included 528 patients diagnosed between October 2009 and December 2021. Clinicopathological characteristics and treatments with or without PORT were analyzed for their impact on outcomes. RESULTS Among 528 patients who underwent radical surgery (median age, 62 years [IQR, 52-69]), 145 (27.5%) also underwent PORT. Multivariate analyses revealed that PORT was associated with improved survival outcomes, whereas moderate-to-poor differentiation, perineural infiltration (PNI), lymphovascular invasion (LVI), and increasing depth of invasion (DOI) were associated with poorer survival outcomes. For patients with moderate-to-poor differentiation, the surgery + PORT group showed improved outcomes compared with the surgery-alone group. After propensity score matching, the results were as follows: overall survival (OS), 97% versus 69%, P = .003; disease-free survival (DFS), 88% versus 50%, P = .001. After excluding cases with PNI/LVI, the differences persisted: OS, 97% versus 82%, P = .040; DFS, 87% versus 64%, P = .012. Similar survival benefits were observed in 104 patients with PNI and/or LVI (OS, 81% v 58%; P = .022; DFS, 76% v 47%; P = .002). In subgroups with DOI >5 mm or close margins, PORT contributed to improved DFS (80% v 64%; P = .006; 92% v 66%; P = .049) but did not significantly affect OS. CONCLUSION Patients with moderately-to-poorly differentiated pT1-2N0M0 OTSCC benefited from PORT. Our study provided evidence that patients with PNI and/or LVI who underwent PORT had improved survival. PORT also offered DFS benefit among patients with DOI >5 mm.