Simultaneous modulated accelerated radiation therapy in the treatment of nasopharyngeal cancer: A local center’s experience

Abstract

Purpose: To evaluate the feasibility, toxicity, and clinical efficacy of simultaneous modulated accelerated radiation therapy boost technique for nasopharyngeal carcinoma. Method and Materials: Seventy-five patients with nasopharyngeal carcinoma were treated with simultaneous modulated accelerated radiation therapy boost technique. Daily fraction of 2.5 Gy and 2.0 Gy were prescribed to the gross tumor volume (GTV) and clinical tumor volume (CTV) to a total dose of 70 Gy and 56 Gy, respectively, in 38 days. In 24 of these patients, GTV was boosted to 80 Gy. Quantitative 99m Tc-pertechnetate salivary scintigraphy was performed by assessing excretion uptake and excretion index of parotid glands. Results: In dosimetry, the mean doses delivered to the GTV, CTV1, and CTV2 were 68.1 Gy, 58.7 Gy, and 54.3 Gy, respectively. An average of 1% of the GTV and 3% of the CTV received less than 90% and 95% of the prescribed dose, respectively, whereas the mean doses delivered to the organ at risk were kept below tolerance limits. The mean doses to the ipsilateral and contralateral parotids were 31.1 Gy and 21.9 Gy, respectively. 99m Tc-pertechnetate salivary scintigraphy showed excretion index and uptake index decreased by 44.6% and 28.3%, respectively, in ipsilateral parotid ( p Conclusions: Simultaneous modulated accelerated radiation therapy yielded superior dose distribution over conventional radiotherapy in nasopharyngeal carcinoma and could be delivered with acceptable toxicity and risky organ sparing. Dose escalation to 80 Gy was safe and feasible. The local-regional control was excellent, and distant metastases remained the main risk.