title: Late toxicities after intensity-modulated radiotherapy for nasopharyngeal carcinoma: patient and treatment-related risk factors.
abstract: BACKGROUND
  The objective of this study is to analyse the factors affecting late toxicity for nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated radiotherapy (IMRT).
  
  
  METHODS
  Seven hundred and eighty-nine consecutive NPC patients treated with IMRT at our centre from January 2003 to February 2008 were retrospectively analysed. Radiotherapy-related complications were categorised using the RTOG Late Radiation Morbidity Scoring Criteria and the Common Terminology Criteria for Adverse Events (Version 3.0). Two hundred and thirty-three patients were treated with IMRT alone (group 1) and 556 patients underwent cisplatin-based chemotherapy (group 2).
  
  
  RESULTS
  Median follow-up was 65 months (range, 4-106 months). The 5-year major late toxicity rate was significantly greater in group 2 than group 1 (63.2% vs 42.0%, P<0.001). Multivariate analyses showed that N category, T category and chemotherapy were significant factors. The maximal dose (Dmax) to the temporal lobe was a significant factor affecting temporal lobe injury (TLI), with a hazard ratio of 1.26 (95% confidence interval (CI), 1.18-1.35; P<0.001) per 1-Gy increase. The 5-year TLI rate increased from 0.8% for 284 lobes with Dmax <65.77 Gy to 27.1% for 176 lobes with greater doses (P<0.001). Logistic regression showed that the hazard ratio attributed to the parotid gland mean dose was 1.36 (95% CI, 1.21-1.53; P<0.001) per 1-Gy increase. Chemotherapy was not a significant factor (P=0.211).
  
  
  CONCLUSIONS
  With the application of IMRT, the incidence of radiation-related complications has been reduced except for TLI. The significant factors affecting the risk of TLI included T category, chemotherapy and Dmax.
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: L
authors.initials: L
authors.lastname: Zeng
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: Y-M
authors.initials: YM
authors.lastname: Tian
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: X-M
authors.initials: XM
authors.lastname: Sun
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: C-Y
authors.initials: CY
authors.lastname: Chen
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: F
authors.initials: F
authors.lastname: Han
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: W-W
authors.initials: WW
authors.lastname: Xiao
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: X-W
authors.initials: XW
authors.lastname: Deng
authors.affiliation: 1] State Key Laboratory Oncology in South China; Collaborative Innovation Center of Cancer Medicine, Guangzhou, People's Republic of China [2] Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, People's Republic of China.
authors.forename: T-X
authors.initials: TX
authors.lastname: Lu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002277:Carcinoma; D002681:China / Q000453:epidemiology; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077274:Nasopharyngeal Carcinoma; D009303:Nasopharyngeal Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000532:radiotherapy*; D009367:Neoplasm Staging; D011832:Radiation Injuries / Q000453:epidemiology / Q000209:etiology*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000706:statistics & numerical data; D012189:Retrospective Studies; D055815:Young Adult