The Impact and Prognostic Significance of Extra-Nodal Extension in Clinically N0 Oral Cancer: A Prospective Clinical Study

Oral cavity squamous cell carcinoma (OCSCC) demonstrates a high propensity to metastasize to regional lymph nodes. Despite technological and scientific advances, identification of pathological adverse features preoperatively remains elusive. This study intended to identify the true occurrence of extra-nodal extension (ENE) in clinically and radiologically N0 OCSCC patients and to investigate its impact and prognostic significance. A prospective, single-centre, non-randomized study was conducted at a tertiary cancer centre in South India to include all untreated operable patients of OCSCC without clinical, radiological, or cytological evidence of nodal metastasis (cN0). All the patients underwent tumor resection surgery with neck dissection and received adjuvant therapy when indicated. Patients were followed up and neck dissection specimens were histopathologically analyzed. The primary outcome was to assess the presence of ENE in cN0 OCSCC patients and its extent. The secondary outcomes were 2-year disease-free survival (DFS) and tumor characteristics. A total of 237 patients with operable OCSCC were evaluated. Out of these, 80 patients who were clinically and radiologically N0 were included in the study and they underwent tumor resection surgery and neck dissection. The final histopathological evaluation revealed that 21.25% of patients (n = 17) had metastatic neck disease and 7.5% of patients (n = 6) had ENE, and all were reported as microscopic ENE. Within the node-positive group, the 2-year DFS for patients with and without ENE were 50% and 90.9%, respectively (p = 0.0362). The results suggest that ENE remains a strong predictor of adverse outcomes, recurrence, and survival in oral cancer patients.