title: Extension of local disease in nasopharyngeal carcinoma detected by magnetic resonance imaging: improvement of clinical target volume delineation.
abstract: OBJECTIVE
  To define by MRI the local extension patterns in patients presenting with nasopharyngeal carcinoma (NPC) and to improve clinical target volume delineation.
  
  
  METHODS
  Consecutive patients (N = 943) with newly diagnosed and untreated NPC were included in this study. All patients underwent MRI of the nasopharynx and neck, which was reviewed by two radiologists.
  
  
  RESULTS
  According to the incidence rates of tumor invasion, the anatomic sites surrounding the nasopharynx were initially classified into three risk grades: high risk (> or = 35%), medium risk (> or = 5-35%), and low risk (< 5%). Incidence rates of tumor invasion into anatomic sites at medium risk were increased, reaching 55.2%, when adjacent high-risk anatomic sites were involved. However, the rates were substantially lower, mostly < 10%, when adjacent high-risk sites were not involved. The incidence rates of concurrent tumor invasion into bilateral sites were < 10%, except in the case of prevertebral muscle involvement (13.1%). Among the 178 incidences of cavernous sinus invasion, there were often two or more simultaneous infiltration routes (60.6%); when only one route was involved, the foramen ovale was the most common (26.4%).
  
  
  CONCLUSIONS
  In patients presenting with NPC, local disease spreads stepwise from proximal sites to more distal sites. Tumors extend quickly through privileged pathways such as neural foramina. The anatomic sites surrounding the nasopharynx are at low risk of concurrent bilateral tumor invasion. Selective radiotherapy of the local disease in NPC may be feasible.
authors.affiliation: State Key Laboratory of Oncology in Southern China, Guangzhou, People's Republic of China.
authors.forename: Shao-Bo
authors.initials: SB
authors.lastname: Liang
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.forename: Li-Zhi
authors.initials: LZ
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Chen
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Mao
authors.forename: Ling-Long
authors.initials: LL
authors.lastname: Tang
authors.forename: Li
authors.initials: L
authors.lastname: Tian
authors.forename: Ai-Hua
authors.initials: AH
authors.lastname: Lin
authors.forename: Meng-Zhong
authors.initials: MZ
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002426:Cavernous Sinus / Q000473:pathology; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009092:Mucous Membrane / Q000473:pathology; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D018570:Risk Assessment; D047368:Tumor Burden; D055815:Young Adult