Extranodal Expansion Of The Lymph Nodes Is An Effective Predictor Of Distant Metastasis Of Nasopharyngeal Carcinoma After Radical Radiotherapy And Chemotherapy

Abstract

Extranodal extension (ENE) of the lymph nodes is a criterion for advanced nodal staging of oropharyngeal and hypopharyngeal carcinoma. The purpose is to investigate whether ENE is a factor affecting distant metastasis of nasopharyngeal carcinoma after radical radiotherapy and chemotherapy. From January 2009 to December 2014, 318 patients of NPC after radical radiotherapy and chemotherapy were enrolled. All patients received radical intensity-modulated radiotherapy. Concurrent chemotherapy was cisplatin intravenous drip every 3 weeks for 4-6cycles.MRI was retrospectively reviewed in all patients and the ENE of the lymph nodes was evaluated in patients with metastatic lymph nodes. According to the tendency of disease metastasis, patients were divided into ascending and descending types. Ascending type (Type A,T3-4N0-1) was defined as advanced local disease and early-stage cervical lymph-node involvement; advanced lymph-node metastases but early -stage local disease was classified as descending type (Type D,T1-2N2-3). Kaplan-Meier methods and Cox proportional hazard models were used to evaluate the impact of different types on distant metastasis free survival. The 5-year distant metastasis-free survival (DMFS) rate of all patients was 85%. There were 143 patients with type A and 175 patients with type D. Compared with type A, type D had worse 5-year DMFS (95% vs 78%; P < 0.05). For type A, univariate analysis and multivariate analysis suggested that ENE was closely related to distant metastasis (P < 0.05). Compared with negative ENE, ENE positive had a higher probability of metastasis within 5 years (DMFS: 99% vs 66.7%; P < 0.05). The independent prognostic factors of type D distant metastasis are ENE and the number of positive lymph nodes. ENEpositive is more likely to have distant metastasis than ENEnegative (DMFS: 84% vs 62.7%). Compared with patients with more than 4 positive lymph nodes, patients with less than 4 positive lymph nodes have significantly better DMFS (83.7% vs 90.9%; P < 0.05 for all). Patients with type D was more likely to metastasize than type A, but no matter how it was typed, ENE was an independent factor affecting distant metastasis and could be considered as a new standard for NPC lymph node staging.