The protective effect of intensity-modulated radiotherapy on the parotid in patients with nasopharyngeal cancer.

Objective To observe the protective effect of intensity-modulated radiotherapy(IMRT) on the parotid in patients with nasopharyngeal cancer.Methods 43 histologicaly proven primary patients with nasopharyngeal cancer were refered to receive radiotherapy.20 patients were treated with IMRT(GTVnx 72 Gy/35 fx) and 23 patients with conventional radiotheraphy(GTVnx 70 Gy/36-37 fx) to the tumor regions.The secretory volume of salivary and the occurrence of xerostomia were observed in two groups and the exposure dose of radiotherapy for parotid were also observed in two groups respectively.Results The average dose of GTVnx in IMRT group was 71.81±1.26 Gy,which was higher than that in conventional group 69.38G±0.26 Gy.After radiotheraphy,the secretory volume of salivary decreased significantly in conventional group than that in IMRT group.Compared with IMRT group,the number of patients with xerostomia in conventional group increased and the symptoms of xerostomia were more seriously.During the three months follow up time,the secretory volume of salivary increased and the symptoms of xerostomia relieved in IMRT group.but there were no difference in conventional group.The average and D50 exposure dose of radiotherapy for parotid were lower than those in conventional group.In IMRT group,the dose was also lower in the contralateral parotid than that in ipsilateral parotid.The difference were obviously(P0.01).Conclusion Using intensity-modulated radiotherapy to treat the patient with nasopharyngeal cancer can secure the high dose in tumor regions and decrease the exposure dose of radiotherapy for parotid,which may abate the impairment of parotid and get early recovery of the parotid function.