Parotid gland function after radiotherapy: the combined michigan and utrecht experience

Int J Radiat Oncol Biol Phys. 2010 Oct 1;78(2):449-53. doi: 10.1016/j.ijrobp.2009.07.1708. Epub 2010 Jan 7.


Purpose: To analyze the combined and updated results from the University of Michigan and University Medical Center Utrecht on normal tissue complication probability (NTCP) of the parotid gland 1 year after radiotherapy (RT) for head-and-neck (HN) cancer.

Patients and methods: A total of 222 prospectively analyzed patients with various HN malignancies were treated with conventional and intensity-modulated RT. Stimulated individual parotid gland flow rates were measured before RT and 1 year after RT using Lashley cups at both centers. A flow ratio <25% of pretreatment was defined as a complication. The data were fitted to the Lyman-Kutcher-Burman model.

Results: A total of 384 parotid glands (Michigan: 157; Utrecht: 227 glands) was available for analysis 1 year after RT. Combined NTCP analysis based on mean dose resulted in a TD(50) (uniform dose leading to 50% complication probability) of 39.9 Gy and m (steepness of the curve) of 0.40. The resulting NTCP curve had good qualitative agreement with the combined clinical data. Mean doses of 25-30 Gy were associated with 17-26% NTCP.

Conclusions: A definite NTCP curve for parotid gland function 1 year after RT is presented, based on mean dose. No threshold dose was observed, and TD(50) was equal to 40 Gy.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Dose-Response Relationship, Radiation
  • Female
  • Head and Neck Neoplasms / radiotherapy*
  • Humans
  • Lethal Dose 50
  • Likelihood Functions
  • Male
  • Michigan
  • Middle Aged
  • Models, Biological
  • Netherlands
  • Parotid Gland / physiopathology
  • Parotid Gland / radiation effects*
  • Prospective Studies
  • Radiotherapy, Intensity-Modulated / adverse effects*
  • Radiotherapy, Intensity-Modulated / methods
  • Salivation / physiology
  • Salivation / radiation effects*
  • Time Factors
  • Xerostomia / etiology
  • Young Adult