title: Submandibular gland-sparing radiation therapy for locally advanced oropharyngeal squamous cell carcinoma: patterns of failure and xerostomia outcomes.
abstract: BACKGROUND
  Saliva from submandibular glands (SMG) is necessary to minimize xerostomia. It is unclear whether SMG can be safely spared in patients undergoing bilateral neck radiotherapy for locally advanced oropharyngeal cancer without increasing the risk of marginal recurrence. We evaluated the outcomes of contralateral submandibular gland (cSMG) sparing intensity-modulated radiation therapy (IMRT).
  
  
  METHODS
  All patients with stage III/IV oropharyngeal squamous cell carcinoma treated with bilateral neck IMRT from 2006-2012 at our institution were included. Appropriately selected patients with favorable primary tumor characteristics and no definite contralateral neck disease were treated with cSMG-sparing IMRT. Patterns of failure and xerostomia outcomes were retrospectively analyzed.
  
  
  RESULTS
  114 patients were treated. 89% had stage IV disease and 89% received definitive radiation therapy. 76 patients (67%) received cSMG sparing IMRT. With a median follow-up of 30 months, there were 10 local, 9 regional, and 10 distant recurrences. 2-year overall survival was 86% and 2-year loco-regional control was 87%. In cSMG spared patients, the mean cSMG dose was 30.7 Gy. Late grade 2+ xerostomia was significantly reduced in the cSMG spared group compared to those without SMG sparing (6 months: 23% vs. 72%, 12 months: 6% vs. 41%, 24 months: 3% vs. 36%, all p < 0.0007). There were no peri-SMG marginal recurrences in the cSMG-spared cohort.
  
  
  CONCLUSIONS
  cSMG sparing IMRT did not increase marginal failures in this series of locally advanced oropharyngeal SCC patients. Xerostomia was significantly reduced in cSMG spared patients.
authors.affiliation: Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA, USA. mgens@uw.edu.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Gensheimer
authors.affiliation: Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA, USA. jayliao@uw.edu.
authors.forename: Jay J
authors.initials: JJ
authors.lastname: Liao
authors.affiliation: Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. agarden@mdanderson.org.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Garden
authors.affiliation: Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA, USA. georgel@uw.edu.
authors.forename: George E
authors.initials: GE
authors.lastname: Laramore
authors.affiliation: Department of Radiation Oncology, University of Washington Medical Center, Seattle, WA, USA. upendra@uw.edu.
authors.forename: Upendra
authors.initials: U
authors.lastname: Parvathaneni
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000401:mortality / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D009959:Oropharyngeal Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology / Q000517:prevention & control*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects* / Q000379:methods; D013363:Submandibular Gland / Q000528:radiation effects*; D014987:Xerostomia / Q000209:etiology / Q000517:prevention & control*; D055815:Young Adult