title: Distant metastasis risk and patterns of nasopharyngeal carcinoma in the era of IMRT: long-term results and benefits of chemotherapy.
abstract: OBJECTIVE
  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.
  
  
  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 subclassification, 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.
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.|Department of Radiation Oncology, Fujian Medical University Union Hospital, Fuzhou, China.
authors.forename: An-Chuan
authors.initials: AC
authors.lastname: Li
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Wei-Wei
authors.initials: WW
authors.lastname: Xiao
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Guan-Zhu
authors.initials: GZ
authors.lastname: Shen
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.|Department of Radiation Oncology, Cancer Center of Guangzhou Medical University, Guangzhou, China.
authors.forename: An-An
authors.initials: AA
authors.lastname: Xu
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.|Department of Radiation Oncology, The First Affiliated Hospital of Clinical Medicine of Guangdong Pharmaceutical University, Guangzhou, China.
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Cao
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Shao-Min
authors.initials: SM
authors.lastname: Huang
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Cheng-Guang
authors.initials: CG
authors.lastname: Lin
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Han
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Xiao-Wu
authors.initials: XW
authors.lastname: Deng
authors.affiliation: Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.
authors.forename: Chong
authors.initials: C
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000556:secondary*; D002277:Carcinoma; D059248:Chemoradiotherapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy; D011379:Prognosis; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents
keywords: chemotherapy; distant metastasis; intensity-modulated radiotherapy; nasopharyngeal carcinoma