title: Patterns of level II node metastasis in nasopharyngeal carcinoma.
abstract: OBJECTIVE
  To explore the pattern of metastasis to level II nodes and its relationship with tumor range in nasopharyngeal carcinoma (NPC) patients by using magnetic resonance imaging.
  
  
  METHODS
  Magnetic resonance images of 618 NPC patients were reviewed. Nodes were classified as metastatic based on size criteria, the presence of nodal necrosis, and extracapsular spread.
  
  
  RESULTS
  Patients (87.9%, 543) had lymphadenopathy, 470 (86.5%) in level IIb and 326 (60.0%) in level IIa, respectively. Incidence of RLN involvement was less than that of level IIb node involvement (72.2% vs. 86.5%) in 543 patients with lymphadenopathy. Cranial boundaries (71.1%) of level IIb nodes was below the caudal border of C1, and 5.1% was below the skull base, while all the cranial boundaries of level IIa nodes were below the caudal edge of C1. Incidence of level IIb and/or level IIa node metastasis had no correlation with primary tumor extension. Incidence of level IIb metastasis did not differ significantly among T1, 2, 3, and 4 disease, nor did that of level IIa node.
  
  
  CONCLUSIONS
  Cervical level IIb nodes were the most commonly involved nodes in NPC. Metastasis to level IIb and level IIa nodes had no correlation with primary tumor extension, or with T stage. Setting the cranial border of level IIb node at the skull base should be considered when delineating nodal target volume.
authors.affiliation: Department of Radiation Oncology, Fudan University, Shanghai, People's Republic of China.
authors.forename: XiaoShen
authors.initials: X
authors.lastname: Wang
authors.forename: LongGen
authors.initials: L
authors.lastname: Li
authors.forename: ChaoSu
authors.initials: C
authors.lastname: Hu
authors.forename: ZhengRong
authors.initials: Z
authors.lastname: Zhou
authors.forename: HongMei
authors.initials: H
authors.lastname: Ying
authors.forename: JianHui
authors.initials: J
authors.lastname: Ding
authors.forename: Yan
authors.initials: Y
authors.lastname: Feng