title: Dose--volume modeling of brachial plexus-associated neuropathy after radiation therapy for head-and-neck cancer: findings from a prospective screening protocol.
abstract: OBJECTIVE
  Data from a prospective screening protocol administered for patients previously irradiated for head-and-neck cancer was analyzed to identify dosimetric predictors of brachial plexus-associated neuropathy.
  
  
  METHODS
  Three hundred fifty-two patients who had previously completed radiation therapy for squamous cell carcinoma of the head and neck were prospectively screened from August 2007 to April 2013 using a standardized self-administered instrument for symptoms of neuropathy thought to be related to brachial plexus injury. All patients were disease-free at the time of screening. The median time from radiation therapy was 40 months (range, 6-111 months). A total of 177 patients (50%) underwent neck dissection. Two hundred twenty-one patients (63%) received concurrent chemotherapy.
  
  
  RESULTS
  Fifty-one patients (14%) reported brachial plexus-related neuropathic symptoms with the most common being ipsilateral pain (50%), numbness/tingling (40%), and motor weakness and/or muscle atrophy (25%). The 3- and 5-year estimates of freedom from brachial plexus-associated neuropathy were 86% and 81%, respectively. Clinical/pathological N3 disease (P<.001) and maximum radiation dose to the ipsilateral brachial plexus (P=.01) were significantly associated with neuropathic symptoms. Cox regression analysis revealed significant dose-volume effects for brachial plexus-associated neuropathy. The volume of the ipsilateral brachial plexus receiving >70 Gy (V70) predicted for symptoms, with the incidence increasing with V70 >10% (P<.001). A correlation was also observed for the volume receiving >74 Gy (V74) among patients treated without neck dissection, with a cutoff of 4% predictive of symptoms (P=.038).
  
  
  CONCLUSIONS
  Dose-volume guidelines were developed for radiation planning that may limit brachial plexus-related neuropathies.
authors.affiliation: Department of Radiation Oncology, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California. Electronic address: amchen@mednet.ucla.edu.
authors.forename: Allen M
authors.initials: AM
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, University of California, Los Angeles, David Geffen School of Medicine, Los Angeles, California.
authors.forename: Pin-Chieh
authors.initials: PC
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Daly
authors.affiliation: Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: Jing
authors.initials: J
authors.lastname: Cui
authors.affiliation: Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: William H
authors.initials: WH
authors.lastname: Hall
authors.affiliation: Department of Radiation Oncology, University of Mississippi School of Medicine, Jackson, Mississippi.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Vijayakumar
authors.affiliation: Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: Theodore L
authors.initials: TL
authors.lastname: Phillips
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of California, Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: D Gregory
authors.initials: DG
authors.lastname: Farwell
authors.affiliation: Department of Radiation Oncology, University of California, Davis, Comprehensive Cancer Center, Sacramento, California.
authors.forename: James A
authors.initials: JA
authors.lastname: Purdy
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001917:Brachial Plexus / Q000528:radiation effects*; D020516:Brachial Plexus Neuropathies / Q000209:etiology / Q000517:prevention & control*; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D006987:Hypesthesia / Q000209:etiology; D008297:Male; D008875:Middle Aged; D037981:Neck Dissection; D009437:Neuralgia / Q000209:etiology; D058958:Organs at Risk / Q000528:radiation effects*; D011446:Prospective Studies; D011832:Radiation Injuries / Q000175:diagnosis / Q000517:prevention & control*; D011836:Radiation Tolerance; D011879:Radiotherapy Dosage; D012044:Regression Analysis; D011795:Surveys and Questionnaires