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.