Pathological primary tumor status, rather than adjuvant therapy, predicts survival outcomes in pT1–3N1M0 oral cavity squamous cell carcinoma: A nationwide cohort study

Background: The eighth edition of the American Joint Committee on Cancer (AJCC) Staging Manual classifies pT1–3N1M0 oral cavity squamous cell carcinoma (OCSCC) as p-Stage III. However, the prognosis within this group is heterogeneous, and the clinical benefit of adjuvant therapy for patients with a single nodal metastasis remains unclear. Here, we analyzed nationwide data from Taiwan to assess survival outcomes and examine the role of adjuvant therapy in this population. Methods: A retrospective analysis of 1324 pT1–3N1M0 OCSCC patients who underwent surgical resection between 2011 and 2021 was conducted using data from the Taiwan Cancer Registry and National Health Insurance Research Database. Cox proportional hazards models were applied to identify independent prognostic factors for disease-specific survival (DSS) and overall survival (OS). Results: Among the cohort, 247 patients (18.7 %) had pT1N1, 699 (52.8 %) had pT2N1, and 378 (28.5 %) had pT3N1 disease. The 5-year DSS rates for pT1N1, pT2N1, and pT3N1 were 82 %, 79 %, and 69 %, respectively, while OS rates were 73 %, 70 %, and 60 % (both p < 0.0001). No significant differences in DSS or OS were observed between surgery alone and adjuvant therapy. In multivariable analysis, pT3N1 disease was independently associated with worse survival outcomes (HR: 1.76, p = 0.0011 for DSS; HR: 1.63, p = 0.0005 for OS), whereas adjuvant therapies were not independent prognostic factors. Conclusion: Among patients with pT1–3N1M0 OCSCC, those presenting with pT3N1 disease demonstrated significantly poorer DSS and OS. Notably, in patients lacking additional adverse pathological features, the omission of adjuvant therapy did not adversely impact survival endpoints.