Intensify modulated radiotherapy (IMRT) for nasopharyngeal carcinoma

Objective: To evaluate the feasibility, toxicity and clinical efficacy of simultaneous modulated accelerated radiation therapy (SMART) for nasopharyngeal carcinoma. Methods: Thirty-eight patients with nasopharyngeal carcinoma were treated by SMART with 2.5 Gy/fraction at gross tumor volume (GTV) to a total dose of 70 Gy and 2.0 Gy/ fraction at the clinical treatment volume(CTV) to a total dose of 56 Gy in 38 days. Quantitative 99mTc-pertechnetate salivary scintigraphy was used to assess the uptake and excretion index (EI, UI) of parotid gland in order to validate the value of IMRT in parotid gland sparing. Results: The mean doses delivered to the GTV and CTV were 67.2 Gy and 57.0 Gy, respectively. An average of 1% of GTV and 2% of CTV received less than 90% or 95% of the prescribed dose. The mean dose to the contralateral parotid were 23 Gy and no significant decline in EI and UI as compared with significant decline in the ipsilateral parotid by 43.6% and 26.3% (P<0.05). Acute toxicity was well tolerated except the high incidence of severe mucositis. No grade IV side effects occurred. Thirty-four patients had complete response (89.5%) while 4 patients had partial response after completion of treatment , giving a 1-year survival rate of 100%. Conclusions: Simultaneous modulated accelerated radiation therapy yields better dose distribution and acceptable toxicity than the traditional radiotherapy in both early and advanced stage nasopharyngeal carcinoma. The preliminary clinical result is encouraging. (authors)