Purpose: To analyze of survival curve and toxicity outcomes for patients treated for nasopharyngeal carcinoma (NPC) by intensity-modulated radiotherapy (IMRT) delivered by helical TomoTherapy (HT).
Materials and methods: Since May 2006, 72 patients with primary NPC were treated. In 67 cases PET-CT was used to help delineate the gross tumor volume (GTV); in 4 of these cases distant metastases in bone, mediastinal lymph nodes and unexpected small neck nodes were detected by high SUV uptake. 3, 22, 19, and 27 patients, respectively, had AJCC stage I to IV disease. Patients received a median total dose of 72 Gy to the GTV, 64.8 Gy to the elective PTV, and 54 Gy to the clinically negative neck region.
Results: At a median follow-up of 41 months (range 0.2 to 67 months), no patient has recurred locally. Two patients with stage IIb disease, both of whom received chemotherapy, recurred regionally. Ten patients developed distant metastases. One died from progressive disease with initial proved bony metastasis. Two patients with stage IIb disease, both of whom received chemotherapy, experienced neck node recurrence. 5-year locoregional control rate was 97%; freedom from distant metastases was 84.6% at 5 years. No evidence of disease was detected in 13 early stage (I/IIa/IIb) patients who did not receive chemotherapy. Acute grade 3 toxicity occurred in four patients and grade 4 in two patients. Late toxicities were low, with no grade 3+ xerostomia, grade 2 xerostomia in two patients (3%), and grade 3 hearing loss in two patients (3%).
Conclusions: HT resulted in excellent long-term disease control and survival in heterogeneous NPC patients. Generally mild acute and late toxicity, with low rates of xerostomia, were obtained. Image-guided HT offers the ability to deliver conformal, OAR-sparing dose distributions to a wide variety of NPC patients with good long-term clinical outcomes.