title: Potential risk factors for jaw osteoradionecrosis after radiotherapy for head and neck cancer.
abstract: BACKGROUND
  To identify potential risk factors for the development of jaw osteoradionecrosis (ORN) after 3D-conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) among patients with newly diagnosed head and neck cancer.
  
  
  METHODS
  This study included 776 patients who underwent 3D-CRT or IMRT for head and neck cancer at the Department of Radiotherapy at the University Hospital Halle-Wittenberg between 2003 and 2013. Sex, dental status prior to radiotherapy, tumor site, bone surgery during tumor resection, concomitant chemotherapy, and the development of advanced ORN were documented for each patient. ORN was classified as grade 3, 4, or 5 according to the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer classification or grade 3 or 4 according to the late effects in normal tissues/subjective, objective, management, and analytic scale. The cumulative incidence of ORN was estimated. Cox regression analysis was used to identify prognostic risk factors for the development of ORN.
  
  
  RESULTS
  Fifty-one patients developed advanced ORN (relative frequency 6.6 %, cumulative incidence 12.4 %). The highest risk was found in patients who had undergone primary bone surgery during tumor resection (hazard ratio [HR] = 5.87; 95 % confidence interval [CI]: 3.09-11.19) and in patients with tumors located in the oral cavity (HR = 4.69; 95 % CI: 1.33-16.52). Sex, dentition (dentulous vs. edentulous), and chemotherapy had no clinically relevant influence.
  
  
  CONCLUSIONS
  In contrast to most previous studies, we noted a low cumulative incidence of advanced ORN. Patients with tumors located in the oral cavity and those who undergo bone surgery during tumor resection prior to RT may be considered a high-risk group for the development of ORN.
authors.affiliation: Department of Diagnostic Imaging and Radiation Medicine, University Clinic, University Leipzig, Leipzig, Germany. thomas.kuhnt@medizin.uni-leipzig.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kuhnt
authors.affiliation: Department of Medical Informatics, Biometry and Epidemiology, University Clinic Essen, Essen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Stang
authors.affiliation: Department of Medical Epidemiology, Biometry and Computer Science Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wienke
authors.affiliation: Department of Radiotherapy, University Clinic, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Vordermark
authors.affiliation: Department of Prosthetic Dentistry, University School of Dental Medicine, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Ramona
authors.initials: R
authors.lastname: Schweyen
authors.affiliation: Department of Prosthetic Dentistry, University School of Dental Medicine, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
authors.forename: Jeremias
authors.initials: J
authors.lastname: Hey
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D005858:Germany / Q000453:epidemiology; D006258:Head and Neck Neoplasms / Q000150:complications / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D015994:Incidence; D007571:Jaw Diseases / Q000453:epidemiology / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D010025:Osteoradionecrosis / Q000453:epidemiology / Q000209:etiology*; D011379:Prognosis; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects*; D012307:Risk Factors; D055815:Young Adult
keywords: Bone surgery; Dental status; Head and neck cancer; Osteoradionecrosis; Radiotherapy; Tumor site