Intensity-modulated Radiotherapy For163Patients With Nasopharyngeal Carcinoma:Treatment Outcomes In A Mono-institutional Experience

Purpose:To report a single institutional experience and treatment results in nasopharyngeal carcinoma patients treated initially with intensity modulated radiotherapy with simultaneous integrated boost (SIB-IMRT)Methods and Materials:A retrospective study was conducted on163histologically-proven, non-metastatic NPC patients who were treated with SIB-IMRT combined with traditional reduced field technique between July2007and December2011. All patients had enhanced MRI or CT before treatment. During the course of treatment,1～2replaninngs were done for all the patients. All plans had target volumes at three dose levels, with a prescribed dose of69.76Gy～74.12Gy to the gross disease, in2.18Gy/fraction over32～34fractions. Patients with stage III/IVdiseases were given concurrent chemotherapy consisting of the intravenous administration of80mg/m2of cisplatin or nedaplatin (day1) for up to3cycles at an interval of3weeks. Adjuvant chemotherapy using a combination of Cisplatin (80mg/m2on Day1) and5-fluorouracil (720mg/m2civ120h)for three cycles at a3-week interval. Acute toxicities were assessed according to the Common Terminology Criteria for Adverse Events v3.0(CTCAE).Late radiation events were graded according to the Radiation Therapy Oncology Group radiation morbidity scoring criteria(RTOG).The Kaplan-Meier method was used to calculate the survival rates, arid Log-rank test was conducted to determine statistical significances. Factors with statistical significance would be put into a multivariate COX regression model. The probability (P) value was2-sided, and P values of <0.05were considered significant.Results:Median patient age was52years, and about75%of them were male. The median follow-up time was25months (range,3-58months).During follow-up, five (3.1%) had local recurrence, eighteen(11%) had distant metastases, and eighteen(11%) died. The2year local recurrence-free, distant metastasis-free and overall survival rates were96.9%,90.2%and92.4%, respectively. No treatment-related death occurred. During concurrent chemoradiation, the most common acute toxicities were mucositis, dermatitisand xerostoma. Grade0～2mucositis, deramatitis and xerostomia occurred in144(88.3%),157(96.3%),and130(80%) patients, respectively. Grade3mucositis, dermatitis, and xerostoma were seen in18(11%),6(3.7%),and33(20%)patients, respectively.Grade4hematologic toxicity was seen in three patients and Grade4mucositis in one patient. The most common late toxicity of163patients who survived for more than2years was xerostomia.Up to24months, only about5%had Grade3and none had Grade4xerostomia. On Cox multivariate analysis, the T stage and clinical stage were the independent prognostic factors for overall survival.Conclusion:SIB-IMRT combined with traditional reduced field technique achieved excellent long-term locoregional control(LRC) and overall survival (OS) in NPC patients,with acceptable acute and late toxicities. On multivariate analysis, the T stage and clinical stage were the independent prognostic factors for overall survival. Distant metastasis remained the main cause of failure. More effective systemic therapy is prompted to reduce the risk of distant metastasis.