Objective:To investigate the protective effect of intensity-modulated radiotherapy (IMRT) on salivary gland function in nasopharyngeal carcinoma (NPC) patients. Methods:In total, 101 NPC patients who were admitted from March 2010 to November 2012 were enrolled in this study. The parotid gland, the submandibular gland, and the oral cavity were sketched as the organs at risk (OARs). The patients were treated with IMRT and were evaluated through a face-to-face interview using a dry mouth assessment ques-tionnaire during the follow-up visits at 3, 6, 12, 18, and 24 months. The dose volume histogram of the salivary gland of the patients was also considered. Results:The mean doses (MDs) in the parotid gland were 37.4 and 33.8 Gy in the affected and uninjured sides, respec-tively. Meanwhile, the MDs in the submandibular glands were 51.6 and 45.7 Gy in the affected and uninjured sides, respectively. The MD of the oral cavity was 38.2 Gy. At 6 months after the treatment, the symptom of xerostomia was significantly improved in 77.2%of the patients (78/101). One year later, only less than 5%of the patients complained of having G3 or higher-grade xerostomia. Conclu-sion:With time, xerostomia significantly improved after the radiotherapy. At least one of the V30 to V35 of the parotid gland was≤50.0%, whereas at least one of the V40 to V45 of the submandibular glands was≤66.7%~50.0%. The MD for the oral cavity should be<40 Gy to effectively protect salivary gland function.

Objective To investigated the protective ways of intensity modulated radiotherapy (IMRT)for submandibular gland function in patients with nasopharyngeal carcinoma.Methods From March 2010 to November 2012,101 patients with nasopharyngeal carcinoma were enrolled into study.They were treated with IMRT and evaluated by face to face dry mouth questionnaire during the follow-up of 3,6,12,18,24 and more than 24 months,meanwhile,their dose volume histogram of submandibular gland were taken into consideration.Results The average contralateral median dose and that of ipsilateral submandibular gland were (45.69±7.22) Gy and (51.64±8.20) Gy,respectively,and the V35,V40,V45,V50 were 95.82 ％,69.99 ％,46.90 ％,25.50 ％,and 100 ％,96.50 ％,82.24 ％,60.98 ％,respectively.There were positive relationship between the xerostomia grading of 3,6,and 12 months after radiotherapy and the average dose of submandibular gland or the V35,V40,V45,V50.After 6 month,the xerostomia in 77.2 ％ (78/101) was significantly improved,and after 12 months,less than 5 ％ of patient complained about G3 or more grade of xerostomia.Conclusions When using IMRT in nasopharyngeal carcinoma,it' s necessary to reduce the irradiated volume and the dose of submandibular gland.It is confined that the median dose of contralateral submandibular gland should be less than 40-45 Gy,and V40 or V45 ≤66.7 ％ or ≤50 ％,which can effectively protect the function of salivary gland.

PURPOSE: This study aims to investigate the feasibility of contouring target volume according to residual tumor and decreasing the dose to the tumor regression field after induction chemotherapy (IC) in locoregionally advanced nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: From August 2009 to August 2013, patients with stage III–IVB NPC were treated with IC and concurrent chemoradiotherapy. Gross tumor volume of nasopharynx (GTVnx)–residual and gross tumor volume of cervical lymph node (GTVnd)–residual were contoured according to post-IC residual primary tumor and any N+ disease, respectively. The tumor regression field was included in CTVnx1/CTVnd1 and prescribed a dose of 60 Gy. Outcomes and toxicities of all patients were evaluated. RESULTS: A total of 57 patients were enrolled. At a median follow-up of 68 months, three cases displayed locoregional recurrence and one case showed both distant metastasis and locoregional recurrence. All locoregional recurrences were in the GTVnx-residual/GTVnd-residual and in-field. The 5-year overall, locoregional relapse-free, distant metastasis-free, and progression-free survival rates were 82.2%, 87.7%, 85.8% and 80.3%, respectively. CONCLUSION: After IC, contouring of GTVnx-residual/GTVnd-residual as residual tumor volume and distribution 60 Gy ofradiation dose to the tumorregression field may be feasible and need further investigation.
Chemoradiotherapy ; Disease-Free Survival ; Follow-Up Studies ; Humans ; Induction Chemotherapy ; Lymph Nodes ; Nasopharynx ; Neoplasm Metastasis ; Neoplasm, Residual ; Radiotherapy, Intensity-Modulated ; Recurrence ; Tumor Burden

Objective: To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), aiming to provide references for the quality control of multi-center clinical trials. Methods: The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the " manual contour group" , and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the " auto+ manual contour group" . The maximum/minimum ratio (MMR) of the PTV and OAR volumes, and the coefficient of variation (CV) for different delineated contours were comparatively evaluated. Results: Large variation was observed in the PTV and OAR volumes in the manual contour group. The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39, with the most significant variation in the PTV_nd (MMR=3.41 and CV=0.39 for the PTV_nd-L). The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67. The MMR of the temporal lobe, spinal cord, temporomandibular joint, optic nerve and pituitary gland exceeded 2.0. Compared with the manual contour group, the average contouring time in the auto+ manual group was shortened by 68% and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37. Conclusions Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers. Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation, whereas the variation in the delineation of small organs remains above 1.5 times. The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.