The Long-term Recovery of Parotid Glands and Oral QOL in Nasopharyngeal Cancer Treated by Intensity-modulated Radiotherapy
Abstract BackgroundXerostomia is one of the most common adverse events of radiotherapy in head and neck cancer patients. The purpose of this study was to evaluate longitudinal volume the change of parotid gland after radiotherapy for nasopharyngeal cancer and the relationship between parotid irradiation dose and xerostomia symptoms.Methods We retrospectively analyzed longitudinal changing of parotid gland volumes in 20 patients treated by intensity-modulated radiotherapy (IMRT). We assessed xerostomia 4 years or more after IMRT by measuring the degree of oral moisture and oral QOL evaluation.ResultsThe relative parotid volumes at 0-6, 7-18, 19-30, 31-42, 43-54 and 55-66 months after IMRT were67.9 ± 10.1%, 67.7 ± 13.6%, 74.3 ± 12.5%, 75.8 ± 12.4%, 78.3 ± 17.4%, and 75.3% ± 17.7%, respectively. The parotid volume had recovered significantly at 31-42 months after IMRT, especially in parotid receiving less than 40 Gy. The mean irradiated dose for bilateral parotids showed negative correlations with oral QOL score and oral moisture. ConclusionThe mean irradiated dose for the parotid should be reduce as much as possible to improve oral QOL long after IMRT.