title: Determining optimal clinical target volume margins in head-and-neck cancer based on microscopic extracapsular extension of metastatic neck nodes.
abstract: OBJECTIVE
  To determine the optimal clinical target volume margins around the gross nodal tumor volume in head-and-neck cancer by assessing microscopic tumor extension beyond cervical lymph node capsules.
  
  
  METHODS
  Histologic sections of 96 dissected cervical lymph nodes with extracapsular extension (ECE) from 48 patients with head-and-neck squamous cell carcinoma were examined. The maximum linear distance from the external capsule border to the farthest extent of the tumor or tumoral reaction was measured. The trends of ECE as a function of the distance from the capsule and lymph node size were analyzed.
  
  
  RESULTS
  The median diameter of all lymph nodes was 11.0 mm (range: 3.0-30.0 mm). The mean and median ECE extent was 2.2 mm and 1.6 mm, respectively (range: 0.4-9.0 mm). The ECE was <5 mm from the capsule in 96% of the nodes. As the distance from the capsule increased, the probability of tumor extension declined. No significant difference between the extent of ECE and lymph node size was observed.
  
  
  CONCLUSIONS
  For N1 nodes that are at high risk for ECE but not grossly infiltrating musculature, 1 cm clinical target volume margins around the nodal gross tumor volume are recommended to cover microscopic nodal extension in head-and-neck cancer.
authors.affiliation: Department of Experimental Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
authors.forename: Smith
authors.initials: S
authors.lastname: Apisarnthanarax
authors.forename: Danielle D
authors.initials: DD
authors.lastname: Elliott
authors.forename: Adel K
authors.initials: AK
authors.lastname: El-Naggar
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Asper
authors.forename: Angel
authors.initials: A
authors.lastname: Blanco
authors.forename: K Kian
authors.initials: KK
authors.lastname: Ang
authors.forename: Adam S
authors.initials: AS
authors.lastname: Garden
authors.forename: William H
authors.initials: WH
authors.lastname: Morrison
authors.forename: David
authors.initials: D
authors.lastname: Rosenthal
authors.forename: Randal S
authors.initials: RS
authors.lastname: Weber
authors.forename: K S Clifford
authors.initials: KS
authors.lastname: Chao
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006258:Head and Neck Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009333:Neck; D012044:Regression Analysis; D012189:Retrospective Studies