Clinical Outcomes of Nasopharyngeal Carcinoma Patients Treated with Adaptive Helical Tomotherapy, A 5-year Experience

The study aims to retrospectively review the survival and toxicity outcomes of adaptive helical tomotherapy (HT) treatment of nasopharyngeal carcinoma (NPC) patients over 5 years.Between February 2010 and September 2017, 67 biopsy-proven non-metastatic NPC patients were analyzed. All patients except one received concurrent chemotherapy and treated with adaptive Simultaneous integrated boost- intensity-modulated radiation therapy (SIB-IMRT). The median age was 48.5 years (range, min: 11 max: 78) with male predominance (82.1% vs. 17.9%). Neck mass was the most common presenting symptom followed by hearing problems (52% and 24%).The mean dose with standard deviation (sd) of D50 to patients' parotid glands and cochleae were 33 ± 11 Gy; 31 ± 11 9 Gy and 37 ± 11 14 Gy; 34 ± 11 14 Gy, respectively. Locoregional progression-free survival (LRRFS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and overall survival (OS) estimated at 2 and 5 years were 83% and 63%, 78.4% and 61.7%, 83% and 69%, 86% and 71%, respectively. Acute Grade 3 or higher dysphagia and mucositis observed in 28 (42%) patients who required daily iv fluid transfusion and/or hyperalimentation. None of the patients had grade 3 and higher mucous membranes and salivary gland toxicity beyond 6 months. Two patients had ≥ grade 3 late toxicity. During the median 51 months (range 2-100) follow up, thirteen patients relapsed (19.4%), six of them (8.9%) recurred locoregionally, and 7 (10.4%) of them developed distant metastasis.The present study reemphasizes that adaptive SIB-IMRT with HT is a good option for the management of NPC with comparable loco-regional control rates and low salivary gland toxicity.