Prognostic impact of extended neck dissection in oral squamous cell carcinoma: a retrospective study

Abstract

Background: Cervical lymph node metastasis with extranodal extension (ENE) is a poor prognostic factor for oral squamous cell carcinoma (OSCC). This study aimed to evaluate the treatment outcomes of OSCC patients who underwent extended neck dissection (ND), requiring resection of non-lymphatic structures for invasive nodal disease. Methods: Patients who underwent extended ND for OSCC at the Department of Oral and Maxillofacial Surgery, Tokyo Medical and Dental University between April 2001 and December 2018 were retrospectively analyzed. Regional recurrence and complication were assessed. The primary outcome variable was 5-year disease-specific survival. Results: A total of 49 patients were included, and regional recurrence was found 18 patients (36.7%). There was no significant difference in the regional recurrence rate, regardless of whether the non-lymphatic structure requiring resection was single or multiple (29.6% vs 45.4%, P = 0.398). The regional recurrence rate was significantly higher in patients who required resection of neurovascular structures than in patients who did not require resection of these structures (64.3% vs 25.7%, P = 0.028). Cox proportional-hazards regression models indicated that types of resected non-lymphatic structures (with neurovascular structures) was the most risk factor for predicting the risk of regional recurrence (P = 0.048, hazard ratio = 2.59, 95% confidence interval: 1.01–6.66). Cox regression analysis to determine independent predictive factors for DSS, revealing that types of resected non-lymphatic structures (P=0.038, HR = 2.58, 95% CI: 1.05–6.33) was independent predictive factors for DSS. Patients who required resection of neurovascular structures had significantly worse the 5-year DSS rate than those who did not (23.4% vs 63.1%; P = 0.014). Complications after extended ND included recurrent nerve paralysis in three patients, facial nerve paralysis in two patients, and chyle leak, fracture of mandible, and urgent tracheostomy due to larynx edema in a patient, respectively. Conclusion: This study suggests that adhesion of metastatic lymph nodes to neurovascular structures is a significant poor prognostic factor for regional recurrence after extended ND. Patients with OSCC with adhesion of metastatic lymph nodes to neurovascular structures require an adequate safety resection margin and intensive postoperative treatment.