title: Is replacement of the supraclavicular fossa with the lower level classification based on magnetic resonance imaging beneficial in nasopharyngeal carcinoma?
abstract: OBJECTIVE
  To investigate the pattern of lymph node metastasis and treatment outcome after intensity-modulated radiotherapy (IMRT) in nasopharyngeal carcinoma (NPC), and assess the possibility of replacing Ho's supraclavicular fossa (SCF) with the lower level (LL; cervical extension below caudal edge of cricoid cartilage) based on magnetic resonance imaging (MRI) as a criterion for N3 disease.
  
  
  METHODS
  We retrospectively reviewed 749 patients with biopsy-proven non-metastatic NPC treated with IMRT. Lymph node metastasis was mapped using the 2013 International Consensus Guidelines.
  
  
  RESULTS
  Cervical lymph node (CLN) laterality, CLN greatest dimension (>60 vs. ⩽60 mm) and Ho's SCF were independent prognostic factors for disease-free survival (DFS) and distant metastasis-free survival (DMFS; P<0.01) in multivariate analysis. Replacing Ho's SCF with the LL was also predictive for DFS and DMFS (P<0.01). Compared to the 7th UICC/AJCC, N-categories based on the LL provided more satisfactory distinction between hazard ratios for distant and disease failure for each N-category. N3a and N3b as defined by the 7th UICC/AJCC had similar DMFS (P=0.31) and DFS (P=0.21).
  
  
  CONCLUSIONS
  Replacing Ho's SCF with the LL is simple and practical. The N-category staging system could be further simplified by merging N3 subcategories.
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Dan
authors.initials: D
authors.lastname: Yue
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Ya-Fei
authors.initials: YF
authors.lastname: Xu
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Lin
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Mao
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Wen-Fei
authors.initials: WF
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Imaging Diagnosis and Interventional Center, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Li-Zhi
authors.initials: LZ
authors.lastname: Liu
authors.affiliation: Department of Medical Statistics and Epidemiology, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Lin
authors.affiliation: Imaging Diagnosis and Interventional Center, Sun Yat-sen University, Guangzhou, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Sun Yat-sen University, Guangzhou, People's Republic of China. Electronic address: majun2@mail.sysu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy; D002277:Carcinoma; D003413:Cricoid Cartilage; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D009333:Neck; D009367:Neoplasm Staging; D010614:Pharynx; D011379:Prognosis; D050397:Radiotherapy, Intensity-Modulated; D016896:Treatment Outcome
keywords: IMRT; MRI; N-category staging system; Nasopharyngeal carcinoma; Neck node levels