Simultaneous modulated accelerated radiation therapy in the treatment of nasopharyngeal cancer

Abstract

To evaluate the toxicity and clinical efficacy of simultaneous modulated accelerated radiation therapy (SMART) technique for nasopharyngeal carcinoma. 110 patients with nasopharyngeal carcinoma underwent boost treatment with SMART at the dose of 2.5 Gy/time for 28 times for gross tumor volume (GTV) with the total dose of 70 Gy and the dose of 2.0 Gy/time once a day and 5 times a week, totally 28 times, with the total dose of 56 Gy for the clinical treatment volume (CTV). The GTV dose for 36 of these patients was boosted to 80 Gy. Follow-up was conducted for 24 months (7 - 44 months). Follow-up showed that the 1, 2, and 3-year survival rates were 97.02%, 88.72%, and 78.27%, respectively. The 1 - 3 year local relapse-free survival rate was 97.94% (95.10% - 100%). The 1, 2, and 3-yea local-regional relapse-free rates and distant metastasis-free rates were 95.21%, 89.83%, 76.10% and 95.38%, 85.71%, and 79.67%, respectively. According to the Fuzhou staging, the 3-year overall survival rate of the stage I - II patients was 100%, while the 3-year survival rate of the stage III patients was 74.33% and the 3-year survival rate of stage IV a patients was 62.96%. The acute toxicity was well tolerated except for the high incidence of severe mucositis. No grade 4 side effects occurred. Most of the patients showed Grade 0 to 1 late toxicity and xerostomia was a common side effect. No increase of toxicity was seen when the GTV dose was increased to 80 Gy. SMART yields superior dose distribution over the traditional radiotherapy in nasopharyngeal carcinoma at the early or advanced stages. The local-regional control was excellent and distant metastasis remains the main risk. Dose escalation to 80 Gy was safe and feasible. Toxicity of SMART is acceptable and tolerable.