title: Proposed lymph node staging system using the International Consensus Guidelines for lymph node levels is predictive for nasopharyngeal carcinoma patients from endemic areas treated with intensity modulated radiation therapy.
abstract: OBJECTIVE
  To propose a lymph node (N) staging system for nasopharyngeal carcinoma (NPC) based on the International Consensus Guidelines for lymph node (LN) levels and MRI-determined nodal variables.
  
  
  METHODS
  The MRI scans and medical records of 749 NPC patients receiving intensity modulated radiation therapy with or without chemotherapy were retrospectively reviewed. The prognostic significance of nodal level, laterality, maximal axial diameter, extracapsular spread, necrosis, and Union for International Cancer Control/American Joint Committee on Cancer (UICC/AJCC) size criteria were analyzed.
  
  
  RESULTS
  Nodal level and laterality were the only independent prognostic factors for distant failure and disease failure in multivariate analysis. Compared with unilateral levels Ib, II, III, and/or Va involvement (hazard ratio [HR] 1), retropharyngeal lymph node involvement alone had a similar prognostic value (HR 0.71; 95% confidence interval [CI] 0.43-1.17; P=.17), whereas bilateral levels Ib, II, III, and/or Va involvement (HR 1.65; 95% CI 1.06-2.58; P=.03) and levels IV, Vb, and/or supraclavicular fossa involvement (HR 3.47; 95% CI 1.92-6.29; P<.01) both significantly increased the HR for distant failure. Thus we propose that the N category criteria could be revised as follows: N0, no regional LN metastasis; N1, retropharyngeal lymph node involvement, and/or unilateral levels Ib, II, III, and/or Va involvement; N2, bilateral levels Ib, II, III, and/or Va involvement; N3, levels IV, Vb, and/or supraclavicular fossa involvement. Compared with the 7th edition of the UICC/AJCC criteria, the proposed N staging system provides a more satisfactory distinction between the HRs for regional failure, distant failure, and disease failure in each N category.
  
  
  CONCLUSIONS
  The proposed N staging system defined by the International Consensus Guidelines and laterality is predictive and practical. However, because of no measurements of the maximal nodal diameter on MRI slices, the prognostic significance of LN size needs further evaluation.
authors.affiliation: Department of Radiation Oncology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China.
authors.forename: Wen-Fei
authors.initials: WF
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Mao
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Yuan-Yuan
authors.initials: YY
authors.lastname: Chen
authors.forename: Mo
authors.initials: M
authors.lastname: Chen
authors.forename: Li-Zhi
authors.initials: LZ
authors.lastname: Liu
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Lin
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
mesh_terms: D002277:Carcinoma / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy / Q000556:secondary*; D059248:Chemoradiotherapy / Q000379:methods; D002681:China; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D038622:Internationality; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy; D009333:Neck; D009367:Neoplasm Staging / Q000379:methods* / Q000592:standards; D017410:Practice Guidelines as Topic; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D047368:Tumor Burden