title: Prognostic value of classifying parapharyngeal extension in nasopharyngeal carcinoma based on magnetic resonance imaging.
abstract: OBJECTIVE
  To subclassify parapharyngeal extension in nasopharyngeal carcinoma (NPC) and investigate its prognostic value and staging categories based on magnetic resonance imaging (MRI).
  
  
  METHODS
  Data from 1504 consecutive NPC patients treated with definitive-intent radiotherapy were analyzed retrospectively. Sites of parapharyngeal extension were defined by MRI. Overall survival (OS), local relapse-free survival (LRFS), and distant metastasis-free survival (DMFS) were calculated by the Kaplan-Meier method and compared with the log-rank test. Hazard consistency and hazard discrimination were determined by multivariate analysis with Cox proportional hazards models.
  
  
  RESULTS
  1104 patients (73.4%) had parapharyngeal extension; 1.7-63.8% had involvement of various anatomic sites. The hazard ratio for death was significantly higher with extensive parapharyngeal extension (lateral pterygoid muscle of masticator space and beyond or parotid space) than with mild extension (medial pterygoid muscle of masticator space, or carotid, prestyloid, and prevertebral or retropharyngeal space). OS, LRFS, and DMFS with extensive parapharyngeal extension were similar to those in T4 disease; OS, LRFS, and DMFS with mild parapharyngeal extension were significantly higher than in those T3 disease (all P ≤ 0.015).
  
  
  CONCLUSIONS
  Parapharyngeal extension in NPC should be subclassified as mild or extensive, which should be regarded as stages T2 and T4 diseases, respectively.
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Guo-Yi
authors.initials: GY
authors.lastname: Zhang
authors.affiliation: Department of Radiation Oncology, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center of Cancer Medicine, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Hu
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Xiang-Ping
authors.initials: XP
authors.lastname: Chen
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.affiliation: Imaging Diagnosis and Interventional Center, State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center of Cancer Medicine, Cancer Center, Sun Yat-sen University, Guangzhou, Guangdong 510060, China.
authors.forename: Li-Zhi
authors.initials: LZ
authors.lastname: Liu
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Wei-Hong
authors.initials: WH
authors.lastname: Wei
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Guo-Sen
authors.initials: GS
authors.lastname: Huang
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Miao-Miao
authors.initials: MM
authors.lastname: Zhou
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Ze-Li
authors.initials: ZL
authors.lastname: Huang
authors.affiliation: Cancer Center, Cancer Research Institute, Foshan Hospital, Sun Yat-sen University, Foshan, Guangdong 528000, China.
authors.forename: Yue-Jian
authors.initials: YJ
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000145:classification* / Q000000981:diagnostic imaging* / Q000401:mortality*; D011859:Radiography; D012189:Retrospective Studies; D015996:Survival Rate