Prognostic value and staging classification of retropharyngeal lymph node metastasis in nasopharyngeal carcinoma patients treated with intensity-modulated radiotherapy

PLoS One. 2014 Oct 10;9(10):e108375. doi: 10.1371/journal.pone.0108375. eCollection 2014.

Abstract

Background: The development of intensity-modulated radiotherapy (IMRT) has revolutionized the management of nasopharyngeal carcinoma (NPC). The purpose of this study was to evaluate the prognostic value and classification of TNM stage system for retropharyngeal lymph node (RLN) metastasis in NPC in the IMRT era.

Material and methods: We retrospectively reviewed data from 749 patients with biopsy-proven, non-metastatic NPC. All patients received IMRT as the primary treatment. Chemotherapy was administered to 86.2% (424/492) of the patients with stage III or IV disease.

Results: The incidence of RLN metastasis was 64.2% (481/749). Significant differences were observed in the 5-year disease-free survival (DFS; 70.6% vs. 85.4%, P<0.001) and distant metastasis-free survival (DMFS; 79.2% vs. 90.1%, P<0.001) rates of patients with and without RLN metastasis. In multivariate analysis, RLN metastasis was an independent prognostic factor for disease failure and distant failure (P = 0.005 and P = 0.026, respectively), but not for locoregional recurrence. Necrotic RLN metastases have a negative effect on disease failure, distant failure and locoregional recurrence in NPC with RLN metastasis (P = 0.003, P = 0.018 and P = 0.005, respectively). Survival curves demonstrated a significant difference in DFS between patients with N0 disease and N1 disease with only RLN metastasis (P = 0.020), and marginally statistically significant differences in DMFS and DFS between N1 disease with only RLN metastasis and other N1 disease (P = 0.058 and P = 0.091, respectively). In N1 disease, no significant differences in DFS were observed between unilateral and bilateral RLN metastasis (P = 0.994).

Conclusions: In the IMRT era, RLN metastasis remains an independent prognostic factor for DFS and DMFS in NPC. It is still reasonable for RLN metastasis to be classified in the N1 disease, regardless of laterality. However, there is a need to investigate the feasibility of classifying RLN metastasis as N1a disease in future by a larger cohort study.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carcinoma
  • Cohort Studies
  • Disease-Free Survival
  • Female
  • Humans
  • Lymph Nodes / pathology*
  • Lymphatic Metastasis / diagnosis
  • Lymphatic Metastasis / pathology*
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / diagnosis
  • Nasopharyngeal Neoplasms / pathology*
  • Nasopharyngeal Neoplasms / radiotherapy*
  • Neoplasm Recurrence, Local / diagnosis
  • Neoplasm Recurrence, Local / pathology
  • Neoplasm Staging
  • Pharynx / pathology*
  • Prognosis
  • Radiotherapy, Intensity-Modulated
  • Retrospective Studies

Associated data

  • figshare/10.6084/M9.FIGSHARE.1120584

Grants and funding

This work was supported by grants from the China Scholarship Council (No. 201308440052, the National Natural Science Foundation of China (No. 81101695 and No. 81071836), the Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme (2010), and the Innovation Team Development Plan of the Ministry of Education (IRT1297). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.