title: Dose-response analysis of parotid gland function: what is the best measure of xerostomia?
abstract: OBJECTIVE
  To describe the dose-response relationships for the different measures of salivary gland recovery following radical radiotherapy for locally advanced head and neck squamous cell cancers (LA-HNSCC).
  
  
  METHODS
  Dosimetric analysis of data from the PARSPORT trial, a Phase III study of conventional RT (RT) and intensity modulated radiotherapy (IMRT) for LA-HNSCC was undertaken to determine the relationship between parotid gland mean dose and toxicity endpoints: high-grade subjective and objective xerostomia and xerostomia-related quality of life scores. LKB-NTCP parameters (TD50, m and n) were generated and tolerance doses (D50) reported using non-linear logistic regression analysis.
  
  
  RESULTS
  Data were available on 63 patients from the PARSPORT trial. Parotid saliva flow rate provided the strongest association between mean dose and recovery, D50=23.4 Gy (20.6-26.2) and k=3.2 (1.9-4.5), R(2)=0.85. Corresponding LKB parameters were TD50=26.3 Gy (95% CI: 24.0-30.1), m=0.25 (0.18-1.0 and n=1). LENTSOMA subjective xerostomia also demonstrated a strong association D50=33.3 Gy (26.7-39.8), k=2.8 (91.4-4.4), R(2)=0.77).
  
  
  CONCLUSIONS
  We recommend using the LENT SOMA subjective xerostomia score to predict recovery of salivation due to its strong association with dosimetry and ease of recording.
authors.affiliation: Head and Neck Unit, The Royal Marsden NHS Foundation Trust, London, UK.
authors.forename: Aisha B
authors.initials: AB
authors.lastname: Miah
authors.forename: Sarah L
authors.initials: SL
authors.lastname: Gulliford
authors.forename: Catharine H
authors.initials: CH
authors.lastname: Clark
authors.forename: Shreerang A
authors.initials: SA
authors.lastname: Bhide
authors.forename: Shane H
authors.initials: SH
authors.lastname: Zaidi
authors.forename: Kate L
authors.initials: KL
authors.lastname: Newbold
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Harrington
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Nutting
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010306:Parotid Gland / Q000502:physiology / Q000528:radiation effects*; D000077195:Squamous Cell Carcinoma of Head and Neck; D014987:Xerostomia / Q000209:etiology*