title: Late consequential surgical bed soft tissue necrosis in advanced oropharyngeal squamous cell carcinomas treated with transoral robotic surgery and postoperative radiation therapy.
abstract: OBJECTIVE
  A subset of patients with oropharyngeal squamous cell carcinoma (OP-SCC) managed with transoral robotic surgery (TORS) and postoperative radiation therapy (PORT) developed soft tissue necrosis (STN) in the surgical bed months after completion of PORT. We investigated the frequency and risk factors.
  
  
  METHODS
  This retrospective analysis included 170 consecutive OP-SCC patients treated with TORS and PORT between 2006 and 2012, with >6 months' of follow-up. STN was defined as ulceration of the surgical bed >6 weeks after completion of PORT, requiring opioids, biopsy, or hyperbaric oxygen therapy.
  
  
  RESULTS
  A total of 47 of 170 patients (28%) had a diagnosis of STN. Tonsillar patients were more susceptible than base-of-tongue (BOT) patients, 39% (41 of 104) versus 9% (6 of 66), respectively. For patients with STN, median tumor size was 3.0 cm (range 1.0-5.6 cm), and depth of resection was 2.2 cm (range 1.0-5.1 cm). Median radiation dose and dose of fraction to the surgical bed were 6600 cGy and 220 cGy, respectively. Thirty-one patients (66%) received concurrent chemotherapy. Median time to STN was 2.5 months after PORT. All patients had resolution of STN after a median of 3.7 months. Multivariate analysis identified tonsillar primary (odds ratio [OR] 4.73, P=.01), depth of resection (OR 3.12, P=.001), total radiation dose to the resection bed (OR 1.51 per Gy, P<.01), and grade 3 acute mucositis (OR 3.47, P=.02) as risk factors for STN. Beginning May 2011, after implementing aggressive avoidance of delivering >2 Gy/day to the resection bed mucosa, only 8% (2 of 26 patients) experienced STN (all grade 2).
  
  
  CONCLUSIONS
  A subset of OP-SCC patients treated with TORS and PORT are at risk for developing late consequential surgical bed STN. Risk factors include tonsillar location, depth of resection, radiation dose to the surgical bed, and severe mucositis. STN risk is significantly decreased with carefully avoiding a radiation dosage of >2 Gy/day to the surgical bed.
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: J Nicholas
authors.initials: JN
authors.lastname: Lukens
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania. Electronic address: alexander.lin@uphs.upenn.edu.
authors.forename: Alexander
authors.initials: A
authors.lastname: Lin
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Victoria
authors.initials: V
authors.lastname: Gamerman
authors.affiliation: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Nandita
authors.initials: N
authors.lastname: Mitra
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Surbhi
authors.initials: S
authors.lastname: Grover
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Erin M
authors.initials: EM
authors.lastname: McMenamin
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Weinstein
authors.affiliation: Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Bert W
authors.initials: BW
authors.lastname: O'Malley
authors.affiliation: Department of Hematology Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Roger B
authors.initials: RB
authors.lastname: Cohen
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Abimbola
authors.initials: A
authors.lastname: Orisamolu
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Peter H
authors.initials: PH
authors.lastname: Ahn
authors.affiliation: Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Otorhinolaryngology-Head and Neck Surgery, University of Pennsylvania, Philadelphia, Pennsylvania; Johns Hopkins University, Baltimore, Maryland. Electronic address: hquon2@jhmi.edu.
authors.forename: Harry
authors.initials: H
authors.lastname: Quon
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis / Q000473:pathology; D016017:Odds Ratio; D009959:Oropharyngeal Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D014066:Palatine Tonsil / Q000473:pathology / Q000528:radiation effects*; D011832:Radiation Injuries / Q000473:pathology; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012044:Regression Analysis; D012189:Retrospective Studies; D012371:Robotics; D014059:Tongue / Q000473:pathology / Q000528:radiation effects*