Evaluation of parotid gland function following intensity modulated radiation therapy for head and neck cancer

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.

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.

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 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 2,750 cGy were significantly lower than the baseline values at all times after IMRT.

We suggest that the total parotid mean dose should be limited to