Evaluation of Xerostomia Following Intensity Modulated Radiotherapy (IMRT) for Head and Neck Cancer Patients

Lee, Seok Ho; Kim, Tae Hyun; Chie, Eui Kyu; Im, Hyun Shil; Im, En Shil; Ryu, Jun Sun; Jung, Yoo Seok; Park, Sung Yong; Kim, Joo Young; Pyo, Hong Ryull; Shin, Kyung Hwan; Kim, Dae Yong; Cho, Kwan Ho

Abstract

PURPOSE: This study was done to evaluate xerostomia following intensity modulated radiotherapy for patients with head and neck cancer, and to analyze the correlation between the dosimetric parameters and xerostomia parameters. MATERIALS AND MEHTODS: From February till October 2003, 13 patients with 3 months of follow-up were evaluated for xerostomia after being treated for head and neck cancer with IMRT. Their median age was 57 years (range: 43~77). Xerostomia were assessed with a 4-question xerostomia questionnaire score (XQS) and a test for salivary flow rates (unstimulated and stimulated). The patients were also given a validated LENT SOMA scale (LSC) questionnaire. The evaluations were completed before radiation therapy (pre-RT) and at 1 and, 3 months after radiation therapy (RT). We evaluated xerostomia at pre-RT, 1 and, 3 months after RT. The association between the xerostomia parameters (XQS and LSC) and salivary flow rates (unstimulated and stimulated: USFR and SSFR) was assessed at 1 and 3 months after RT.
RESULTS
All 13 patients showed no significant changes in XQS, LSC and Salivary Flow rates. As a result, we couldn`t find out about xerostomia development. Based on the total mean parotid dose, 3,500 cGy, we divided these patients into two groups. The 8 patients (<3,500 cGy) showed no significant changes in XQS, LSC and Salivary Flow rates. However, in 5 patients (> or =3,500 cGy), there was a significant increase in USFR and, SSFR at 3 months after RT, and for the XQS and, LSC at 1 and 3 months after RT. The correlation between XQS and, LSC, and USFR and, SSFR in all patients (13) was significant at 3 months after RT. The correlation had a tendency to the decrease for USFR and, SSFR in proportion to the increase of XQS and, LSC.
CONCLUSION
Based on the results of this study, IMRT seem to be an effective treatment to significantly decrease the xerostomia. XQS and, LSC seem to be a effective tool for predicting the xerostomia. A total parotid gland mean dose of <3,500 cGy should be a planning goal if substantial sparing of the gland function is desired. Furthermore, patients should be enrolled in a study to define a more accurate threshold dose for the parotid gland.