title: Elective lymph node irradiation with intensity-modulated radiotherapy: is conventional dose fractionation necessary?
abstract: OBJECTIVE
  Intensity-modulated radiation therapy (IMRT) is the standard of care for head-and-neck cancer (HNC). We treated patients with HNC by delivering either a moderate hypofractionation (MHF) schedule (66 Gy at 2.2 Gy per fraction to the gross tumor [primary and nodal]) with standard dose fractionation (54-60 Gy at 1.8-2.0 Gy per fraction) to the elective neck lymphatics or a conventional dose and fractionation (CDF) schedule (70 Gy at 2.0 Gy per fraction) to the gross tumor (primary and nodal) with reduced dose to the elective neck lymphatics. We analyzed these two cohorts for treatment outcomes.
  
  
  METHODS
  Between November 2001 and February 2009, 89 patients with primary carcinomas of the oral cavity, larynx, oropharynx, hypopharynx, and nasopharynx received definitive IMRT with or without concurrent chemotherapy. Twenty patients were treated using the MHF schedule, while 69 patients were treated with the CDF schedule. Patient characteristics and dosimetry plans were reviewed. Patterns of failure including local recurrence (LR), regional recurrence (RR), distant metastasis (DM), disease-free survival (DFS), overall survival (OS), and toxicities, including rate of feeding tube placement and percentage of weight loss, were reviewed and analyzed.
  
  
  RESULTS
  Median follow-up was 31.2 months. Thirty-five percent of patients in the MHF cohort and 77% of patients in the CDF cohort received chemotherapy. No RR was observed in either cohort. OS, DFS, LR, and DM rates for the entire group at 2 years were 89.3%, 81.4%, 7.1%, and 9.4%, respectively. Subgroup analysis showed no significant differences in OS (p = 0.595), DFS (p = 0.863), LR (p = 0.833), or DM (p = 0.917) between these two cohorts. Similarly, no significant differences were observed in rates of feeding tube placement and percentages of weight loss.
  
  
  CONCLUSIONS
  Similar treatment outcomes were observed for MHF and CDF cohorts. A dose of 50 Gy at 1.43 Gy per fraction may be sufficient to electively treat low-risk neck lymphatics.
authors.affiliation: Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Meena
authors.initials: M
authors.lastname: Bedi
authors.forename: Selim
authors.initials: S
authors.lastname: Firat
authors.forename: Vladimir A
authors.initials: VA
authors.lastname: Semenenko
authors.forename: Christopher
authors.initials: C
authors.lastname: Schultz
authors.forename: Patrick
authors.initials: P
authors.lastname: Tripp
authors.forename: Roger
authors.initials: R
authors.lastname: Byhardt
authors.forename: Dian
authors.initials: D
authors.lastname: Wang
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D004750:Enteral Nutrition / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007822:Laryngeal Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D015182:Lymphatic Irradiation / Q000009:adverse effects / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D010610:Pharyngeal Neoplasms / Q000188:drug therapy / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods* / Q000401:mortality; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult