Distant metastasis risk and patterns of nasopharyngeal carcinoma in the era of IMRT: long-term results and benefits of chemotherapy

// An-Chuan Li 1,2,* , Wei-Wei Xiao 1,* , Guan-Zhu Shen 1,* , Lin Wang 1 , An-An Xu 1,3 , Yan-Qing Cao 1,4 , Shao-Min Huang 1 , Cheng-Guang Lin 1 , Fei Han 1 , Xiao-Wu Deng 1 and Chong Zhao 1 1 Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China 2 Department of Radiation Oncology, Fujian Medical University Union Hospital, Fuzhou, China 3 Department of Radiation Oncology, Cancer Center of Guangzhou Medical University, Guangzhou, China 4 Department of Radiation Oncology, The First Affiliated Hospital of Clinical Medicine of Guangdong Pharmaceutical University, Guangzhou, China * These authors have contributed equally to this work Correspondence to: Fei Han, email: // Xiao-Wu Deng, email: // Chong Zhao, email: // Keywords : nasopharyngeal carcinoma, distant metastasis, intensity-modulated radiotherapy, chemotherapy Received : March 24, 2015 Accepted : May 22, 2015 Published : May 28, 2015 Abstract Purpose: To report the distant metastasis (DM) risk and patterns for nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiotherapy (IMRT) and to analyze the benefits of chemotherapy based on DM risk. Materials and Methods: 576 NPC patients were analyzed. The DM rates were calculated using the Kaplan-Meier method, and the log-rank test was used to compare differences. The patients were divided into different risk subclassifications according to DM hazard ratios. Results: 91 patients developed DM after treatment, with bone as the most common metastatic sites. 82.4% of DMs occurred within 3 years of treatment. Patients were classified as low-risk, intermediate-risk and high-risk, and the corresponding 5-year DM rates were 5.1%, 13.1% and 32.4%, respectively ( P < 0.001). Chemotherapy failed to decrease the DM rate in the low-risk subclassification, but decreased the DM risk in the intermediate-risk subclassification ( P = 0.025). In the high-risk subclassificaiton, the DM rate was 31.9% though chemotherapy was used, which was significantly higher than that of other two subclassifications. Conclusions: DM is the dominant treatment failure in NPC treated by IMRT, with similar occurrence times and distributions to those that occurred in the era of conventional radiotherapy. Further studies on treatment optimization are needed in high-risk patients.