title: Elective Nodal Irradiation and Patterns of Failure in Head and Neck Cancer After Primary Radiation Therapy.
abstract: OBJECTIVE
  The delineation of elective clinical target volumes in head and neck cancer (HNC) is important; however, the extent of lymph node levels necessary to include is debated. A comprehensive analysis of recurrence patterns in a large cohort of patients with HNC was performed, with an emphasis on recurrence in the retropharyngeal region and level IB.
  
  
  METHODS
  From 2005 to 2012, 942 patients with oropharyngeal, hypopharyngeal, laryngeal or oral cavity carcinomas were curatively treated with primary radiation therapy. The median follow-up period was 34 months, and 77% of the patients underwent intensity modulated radiation therapy. The retropharyngeal region was only routinely included in cases of involvement of the posterior pharynx wall and level IB only in cases of involvement of the oral cavity. In patients with regional recurrence, the anatomic site of the recurrence was assessed from the surgical descriptions or computed tomography scans and compared with the original radiation treatment plan (available from 2007 onward). The p16 status was available for 282 oropharynx carcinoma cases, with 65% p16-positive.
  
  
  RESULTS
  Of the 942 patients, 376 (40%) developed recurrences: 228 (24.2%) local, 123 (13.1%) regional, and 109 (11.6%) distant. In 700 patients with available treatment plans, retropharyngeal and level IB recurrence was observed in 2 and 7 patients, respectively. Eight patients (1.1%) had recurrence in a lymph node level not included in their primary treatment plan. For oropharynx carcinoma, the locoregional control rate (90% vs 70%) but not distant control rate (92% vs 87%), was significantly better in the p16-positive than in the p16-negative patients. Although fewer recurrences developed in the p16-positive group, patients with recurrence of p16-positive tumors were more likely to develop recurrence in distant sites.
  
  
  CONCLUSIONS
  Retropharyngeal or level IB recurrence after primary HNC radiation therapy is rare. Thus, inclusion of these regions in the elective treatment volumes should be limited to patients with involvement of the posterior pharyngeal wall or oral cavity.
authors.affiliation: Department of Oncology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Julie
authors.initials: J
authors.lastname: Kjems
authors.affiliation: Department of Oncology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Anita B
authors.initials: AB
authors.lastname: Gothelf
authors.affiliation: Department of Oncology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Katrin
authors.initials: K
authors.lastname: Håkansson
authors.affiliation: Department of Oncology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Lena
authors.initials: L
authors.lastname: Specht
authors.affiliation: Department of Oncology, Rigshospitalet, Copenhagen, Denmark.
authors.forename: Claus A
authors.initials: CA
authors.lastname: Kristensen
authors.affiliation: Department of Oncology, Rigshospitalet, Copenhagen, Denmark. Electronic address: jeppe.friborg@regionh.dk.
authors.forename: Jeppe
authors.initials: J
authors.lastname: Friborg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D019941:Cyclin-Dependent Kinase Inhibitor p16; D005260:Female; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000532:radiotherapy; D007822:Laryngeal Neoplasms / Q000532:radiotherapy; D015182:Lymphatic Irradiation; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000532:radiotherapy; D009363:Neoplasm Proteins / Q000032:analysis; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D009959:Oropharyngeal Neoplasms / Q000532:radiotherapy; D010614:Pharynx; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies; D013997:Time Factors; D017211:Treatment Failure
chemical_list: C000614131:CDKN2A protein, human; D019941:Cyclin-Dependent Kinase Inhibitor p16; D009363:Neoplasm Proteins