title: Patterns of long-term swallowing dysfunction after definitive radiotherapy or chemoradiation.
abstract: OBJECTIVE
  To identify patterns of long-term, radiation-induced swallowing dysfunction after definitive radiotherapy with or without chemotherapy (RT or CHRT) and to determine which factors may explain these patterns over time.
  
  
  METHODS
  The study population consisted of 238 consecutive head and neck cancer patients treated with RT or CHRT. The primary endpoint was ⩾grade 2 swallowing dysfunction at 6, 12, 18 and 24months after treatment. Cluster analysis was used to identify different patterns over time. The differences between the mean dose to the swallowing organs at risk for each pattern were determined by using dose maps.
  
  
  RESULTS
  The cluster analysis revealed five patterns of swallowing dysfunction: low persistent, intermediate persistent, severe persistent, transient and progressive. Patients with high dose to the upper pharyngeal, laryngeal and lower pharyngeal region had the highest risk of severe persistent swallowing dysfunction. Transient problems mainly occurred after high dose to the laryngeal and lower pharyngeal regions, combined with moderate dose to the upper pharyngeal region. The progressive pattern was mainly seen after moderate dose to the upper pharyngeal region.
  
  
  CONCLUSIONS
  Various patterns of swallowing dysfunction after definitive RT or CHRT can be identified over time. This could reflect different underlying biological processes.
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Miranda E M C
authors: ME
authors: Christianen
authors: Department of Otolaryngology-Head and Neck Surgery, VU University Medical Center Amsterdam, The Netherlands.
authors: Irma M
authors: IM
authors: Verdonck-de Leeuw
authors: Department of Radiation Oncology, VU University Medical Center Amsterdam, The Netherlands.
authors: Patricia
authors: P
authors: Doornaert
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Olga
authors: O
authors: Chouvalova
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Roel J H M
authors: RJ
authors: Steenbakkers
authors: Department of Radiation Oncology, VU University Medical Center Amsterdam, The Netherlands.
authors: Phil W
authors: PW
authors: Koken
authors: Department of Otolaryngology-Head and Neck Surgery, VU University Medical Center Amsterdam, The Netherlands.
authors: C René
authors: CR
authors: Leemans
authors: Department of Medical Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Sjoukje F
authors: SF
authors: Oosting
authors: Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Jan L N
authors: JL
authors: Roodenburg
authors: Department of Otolaryngology-Head and Neck Surgery, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Bernard F A M
authors: BF
authors: van der Laan
authors: Department of Radiation Oncology, VU University Medical Center Amsterdam, The Netherlands.
authors: Ben J
authors: BJ
authors: Slotman
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands.
authors: Hendrik P
authors: HP
authors: Bijl
authors: Department of Radiation Oncology, University of Groningen, University Medical Center Groningen, The Netherlands. Electronic address: j.a.langendijk@umcg.nl.
authors: Johannes A
authors: JA
authors: Langendijk
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D059248:Chemoradiotherapy / Q000009:adverse effects; D003680:Deglutition Disorders / Q000209:etiology*; D018450:Disease Progression; D005260:Female; D006258:Head and Neck Neoplasms / Q000628:therapy*; D006801:Humans; D007830:Larynx / Q000528:radiation effects; D008297:Male; D008875:Middle Aged; D010614:Pharynx / Q000528:radiation effects; D011446:Prospective Studies; D011832:Radiation Injuries / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects
keywords: Head and neck cancer; Long-term patterns; Radiotherapy; Swallowing dysfunction