Necessity Of Adjuvant Radiotherapy For Pn1 Oral Squamous Cell Carcinoma

To identify pN1 oral squamous cell carcinoma (OSCC) patients without adverse pathologic features benefiting from adjuvant radiotherapy (RT) through integrated analysis of T stage and lymph node yields (LNY). We conducted a retrospective analysis of 231 pN1 OSCC patients treated at 3 institutions (2000-2022). Patients were stratified by T-stage (T1-2 and T3-4) and LNY (≤20 and >20). Survival outcomes were analyzed using Kaplan-Meier curves. Prognostic outcomes were assessed using disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS). No significant survival differences were observed between RT group and NRT group (DFS: 59.5% vs. 58.3%, p=0.938; OS: 73.1% vs. 75.0%, p=0.936; DSS: 74.9% vs. 76.7%, p=0.914). While RT provided no survival benefit to T1-2 patients (DFS: p=0.084; OS: p=0.053; DSS: p=0.072), it improved survival in T3-4 patients (DFS: p=0.030; OS: p=0.034; DSS: p=0.049). Noteworthy among T3-4 patients, RT benefit was confined to those with low LNY (DFS: p=0.007; OS: p=0.022; DSS: p=0.024), whereas patients with high LNY cannot benefit from RT (DFS: p=0.963; OS: p=0.957; DSS: p=0.957). Adjuvant radiotherapy for OSCC is only recommended in low LNY patients of pT3-4pN1, however, it is not indicated for those with either pT1-2N1 or high LNY.