title: Unilateral versus bilateral irradiation in squamous cell head and neck cancer in relation to patient-rated xerostomia and sticky saliva.
abstract: OBJECTIVE
  To investigate the association between radiation technique with patient-rated moderate and severe xerostomia and sticky saliva.
  
  
  METHODS
  One hundred and fifty patients treated with bilateral or unilateral irradiation for head and neck cancer were included. The salivary glands and the oral cavity were delineated on plannings-CT scans. Xerostomia and sticky saliva were assessed using the EORTC QLQ-H&N35 questionnaire at baseline and 6 and 12 months.
  
  
  RESULTS
  At 6 months a significant association between radiation technique and the mean parotid dose (MD(parb)) and xerostomia was observed (Odds ratio (OR)-technique: 2.55; p=0.04 and OR-MD(parb): 1.04; p=0.009). Considering the individual salivary glands, only the mean dose in the contralateral parotid gland (MD(parcl)) is associated with xerostomia (OR: 1.04; p<0.0001). Moreover, the threshold dose for a 50% probability (P50) on xerostomia increased from 21 Gy with bilateral to 44 Gy for unilateral irradiation.
  
  
  CONCLUSIONS
  Both technique and MD(parb) influence the risk of xerostomia in irradiated patients. Of all individual salivary glands, only MD(parcl) is of utmost importance for xerostomia. The shift in the P50 observed for xerostomia suggests that sparing of the contralateral parotid gland is compensated by hyperfunction of the contralateral parotid gland.
authors: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands. a.p.jellema@umcutrecht.nl
authors: Anke Petra
authors: AP
authors: Jellema
authors: Ben J
authors: BJ
authors: Slotman
authors: Patricia
authors: P
authors: Doornaert
authors: C René
authors: CR
authors: Leemans
authors: Johannes A
authors: JA
authors: Langendijk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D015331:Cohort Studies; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011878:Radiotherapy / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012463:Saliva / Q000528:radiation effects*; D014987:Xerostomia / Q000209:etiology*