Preliminary Analysis of Intensity Modulated Radiation Therapy for 20 Patients with Nasopharyngeal Carcinoma / 中国肿瘤临床

ABSTRACT

Objective:To report the preliminary results of intensity modulated radiation therapy(IMRT)for 20 nasopharyngeal carcinoma patients.Methods:A total of 20 patients with nasopharyngeal carcinoma received IMRT in our hospital between January 2007 and April 2008.Five patients were of stage Ⅱ,13 patients were of stage Ⅲ,and 2 patients were of stage Ⅳ.The prescribed dose 69.96 Gy was delivered to the gross tumor volume(PTV)and positive neck nodes(PTVnd);59.36 Gy to the clinical target volume(PTV1),covering the upper neck and area around the nasopharynx;and 50.96 Gy to the low neck and supreclavicular area (PTV2).The dose to 50% of the parotid was≤35 Gy.The maximum dose to the lens.pituitary gland,temporo-mandibular joint,mandible,and temporal lobe was 9,54,60,70,and 60 Gy.The maximum dose to the brainstem,spinal cord,optic nerve and optic chiasma(PRV)was 54,40,54,and 54 Gy,respectively.All of the patients received 1 or 2 circles of chemothrapy before IMRT.Results:The median follow-up time was 14 months.The one-year overall survival was 94.1%.One patient died of osseous metastasis and respiratory failure and 3 patients developed distant metastasis.Acute toxicity was mostly Grade Ⅰ to Grade Ⅱ.Seventeen patients had grade Ⅰ xerostomia.Three patients suffered from grade Ⅰ acute oral mucosa reaction and 12 patients had grade Ⅱ acute oral mucosa reaction.Analysis of the dose-volume histograms (DVHs) showed that the mean dose delivered to the PTV,PTVnd,PTV1 and PTV2 was 73.4,74.1,67.8,and 54.1 Gy,respectively.The median dose to 50% of the right and left parotid glands was 43.9 Gy and 41.9 Gy,respcetively.The average value of maximum dose to the left and right lens was 8.06 and 8.12 Gy,respectively.The average value of maximum dose to the brainstem,spinal cord,left and right optic nerve and optic chiasma PRV was 60.6,46.6,50.0,55.0,and 56.0 Gy,respectively.Conclusion:IMRT can achieve satisfactory dose distdbution to nasopharyngeal carcinoma and surrounding tissues in NPC patients,protect normal tissues during the treatment and improve local control rate.