title: Evaluation of parotid gland function following intensity modulated radiation therapy for head and neck cancer.
abstract: OBJECTIVE
  This study was undertaken to determine the parotid gland tolerance dose levels following intensity modulated radiation therapy (IMRT) for treating patients who suffered with head and neck cancer.
  
  
  METHODS
  From February 2003 through June 2004, 34 head and neck patients with 6 months of follow-up were evaluated for xerostomia after being treated by IMRT. Their median age was 59 years (range: 29~78). Xerostomia was assessed using a 4-question xerostomia questionnaire score (XQS) and a test for the salivary flow rates (unstimulated and stimulated: USFR and SSFR, respectively). The patients were also given a validated LENT SOMA scale (LSS) questionnaire. Evaluations were performed before IMRT and at 1, 3 and 6 months after IMRT.
  
  
  RESULTS
  All 34 patients showed significant changes in the XQS, LSS and Salivary Flow rates (USFR and SSFR) after IMRT. No significant changes in the XQS or LSS were noted in 12 patients who received a total parotid mean dose of <or=3,100 cGy at 1, 3 and 6 months post-IMRT relative to the baseline values. However, for the 22 patients who received >3,100 cGy, significant increases in the XQS and LSS were observed. The USFR and SSFR from the parotid glands in 7 patients who received <or=2,750 cGy were significantly preserved at up to 6 months after IMRT. However, the USFR and SSFR in 27 patients who were treated with >2,750 cGy were significantly lower than the baseline values at all times after IMRT.
  
  
  CONCLUSIONS
  We suggest that the total parotid mean dose should be limited to <or=2,750 cGy to preserve the USFR and SSFR and so improve the subsequent quality of life.
authors.affiliation: Research Institute and Hospital, National Cancer Center, Goyang, Korea.
authors.forename: Seok Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Tae Hyun
authors.initials: TH
authors.lastname: Kim
authors.forename: Joo Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Sung Yong
authors.initials: SY
authors.lastname: Park
authors.forename: Hong Ryull
authors.initials: HR
authors.lastname: Pyo
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Shin
authors.forename: Dae Yong
authors.initials: DY
authors.lastname: Kim
authors.forename: Joo Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Kwan Ho
authors.initials: KH
authors.lastname: Cho