Intensity Modulated Radiotherapy For Patients With Nasopharyngeal Carcinoma Of The Parotid Gland Function Protection

Objective: To study intensity modulated radiotherapy for patients with nasopharyngeal carcinoma of the parotid gland function protectionMethods: 36 NPC patients were divided into intensity modulated radiation therapy (IMRT therapy group) group and conventional fraction (contrast group) group by random balanced design. Each group has 18 patients. Therapy group was given to a total dose of 72.0Gy to Planning Gross Tumor Volume of nasopharyngeal. Contrast group was given with a total dose of 70.0Gy, daily fraction is 2.0Gy, five times a week. Before treatment and 3 months,6months,9months,1-year,2-years after therapy all patients performed parotid imaging and both uptake index(UI) and excretion index(EI) after acid stimulation were calculated. By the use of the dose-volume histogram (DVH) to analysis the dose ofparotid.Results:1. UI and EI of IMRT therapy group at the end of therapy declined by 22.4% and 35.9% respectively. By contrast group declined by 43.2%and 80.6%, 2 years after the treatment therapy group these figure retum to 96.2% and 95.3%, The contrast group lose the parotid function permanently, UI declined by 93.0%, lose excrection function basically.2. The symptom of xerostomia was mild at the end of radiotherapy in the IMRT group, 2 patients did not have xerostomia, gradeâ… was 66.7%, gradeâ…¡was 11.1%, gradeâ…¢was 11.1%. Acute toxicity was well tolerated. The symptom of xerostomia was 22.2%,33.3%,44.4%in the contrast group, acute toxicity was worse.3. 16 patients in the IMRT group had complete remission, 2 had partial remission. 12 patients in the contrast group had complete remission, 6 had partial remission. The 2-year estimates of local progression-free, local-regional progression-free, and distant metastasis-free rates 94.4%, 88.9 %and94.4%. The 2-year survival rate was 94.4%. The contrast group was 88.9%,83.4%and83.4%. The 2-year survival rate was77.8%.Conclusion:1. IMRT can spared more parotid glands than CF and thus protect paroid function effectively.2. IMRT can decrease the acute toxicity effectively.3. IMRT can elevate the therapeutic effect in the near future and survival rate.