title: Positron emission tomography-computed tomography before treatment is highly prognostic of distant metastasis in nasopharyngeal carcinoma patients after intensity-modulated radiotherapy treatment: a prospective study with long-term follow-up.
abstract: OBJECTIVE
  The utility of [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in the prediction of distant metastasis after definitive treatment for non-disseminated NPC patients is not clear. We prospectively investigated the prognostic significance of (18)F-FDG PET-CT performed before treatment for the distant metastasis-free survival (DMFS) of NPC patients treated with intensity-modulated radiotherapy (IMRT) ± chemotherapy.
  
  
  METHODS
  The results of PET-CT scans performed at initial diagnosis were recorded and analyzed prospectively. Patients then received standard treatment per protocol independent of the PET-CT result. IMRT was administered to the nasopharynx and neck. Early stage patients received IMRT alone, whereas loco-regionally advanced patients received concurrent chemoradiation. Patient outcomes were evaluated.
  
  
  RESULTS
  One hundred and seventy-nine patients were analyzable. DM occurred in 33 patients and the 3-year DMFS rate of the whole cohort was 84.1%. The cut-off of the SUVmax at the primary site (SUVmax-P) for DMFS was 10.22 by ROC curve. The 3-year DMFS rates of the higher and lower SUVmax-P groups (SUVmax-P⩽or>10.22) were 93.2% and 75.1%, respectively, with an 18.1% difference (P=0.003). Multivariate analysis indicated that SUVmax-P was a risk factor independently associated with DMFS (HR, 2.672; 95%CI, 1.236-5.776; P=0.012) and OS (HR, 2.417; 95%CI, 1.313-4.448; P=0.005). Subgroup analysis indicated that the 5-year DMFS and OS in loco-regionally advanced patients with SUVmax-P⩽10.22 were similar to those of early stage patients, whereas those of loco-regionally advanced patients with SUVmax-P>10.22 patients predicted worse outcome.
  
  
  CONCLUSIONS
  SUVmax-P is a useful biomarker to predict distant metastasis of NPC patients treated with IMRT. Combining SUVmax-P with tumor overall stage, a more precise picture could be obtained to predict treatment outcome.
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: WeiWei
authors: W
authors: Xiao
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China; Department of Radiotherapy, Affiliated Cancer Hospital of Guangzhou Medical University, China.
authors: AnAn
authors: A
authors: Xu
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: Fei
authors: F
authors: Han
authors: Department of Nuclear Medicine, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: XiaoPing
authors: X
authors: Lin
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: LiXia
authors: L
authors: Lu
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: GuanZhu
authors: G
authors: Shen
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: ShaoMin
authors: S
authors: Huang
authors: Department of Nuclear Medicine, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China.
authors: Wei
authors: W
authors: Fan
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China. Electronic address: dengxw@sysucc.org.cn.
authors: XiaoWu
authors: X
authors: Deng
authors: Department of Radiotherapy, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Guangzhou, China. Electronic address: zhaochong@sysucc.org.cn.
authors: Chong
authors: C
authors: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009303:Nasopharyngeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D049268:Positron-Emission Tomography; D011379:Prognosis; D011446:Prospective Studies; D050397:Radiotherapy, Intensity-Modulated; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Distant metastasis; IMRT; Nasopharyngeal carcinoma; PET-CT; Prospective