• Haojun Chen, Yimin Li, Hua Wu, Long Sun, Qin Lin, Long Zhao, and Hanxiang An.
• Department of Nuclear Medicine, Xiamen Cancer Center, the First Affiliated Hospital of Xiamen University, Xiamen, China, leochen0821@stu.xmu.edu.cn.
• Strahlenther Onkol. 2015 Feb 1; 191 (2): 141-52.

PurposeThe purpose of this work was to investigate the prognostic value of response analysis using early 3'-deoxy-3'-[(18)F]-fluorothymidine ((18)F-FLT) PET/CT in esophageal squamous cancer patients and make a comparison with [(18)F]-fluorodeoxyglucose ((18)F-FDG) PET/CT.Patients And MaterialsFor 34 patients with esophageal squamous cell cancer, both (18)F-FLT PET/CT and (18)F-FDG PET/CT scans were performed at baseline (pre), 4 weeks after the start of radiotherapy or chemoradiotherapy (interim), and 2 weeks after therapy completion (final). SUVmax1, SUVmax2, and SUVmax3 represent SUVmax (SUV: standard uptake values) measured on the pre, interim, and final scans, respectively. GTVFLT-PET and GTVFDG-PET (GTV: gross tumor volume) were measured on the pre and interim scans. ΔSUV/ΔGTV represents the fractional changes of SUVmax/GTV between two different time points. PET parameters were evaluated for correlations with outcome.ResultsRegarding (18)F-FLT PET/CT, according to receiver operating characteristic (ROC) curve analysis, parameters for predicting 2-year progression-free survival (PFS) and locoregional control (LRC) showed the highest area under curve (AUC) on interim (18)F-FLT PET/CT scans (ΔSUV12, AUC of 0.812 for PFS, 0.775 for LRC, with a cutoff of 60 %; P = 0.008), compared with the parameters on pre and final scans. Patients with a ΔSUV12 greater than 60 %, who were defined as interim PET-negative group, were associated with better 2-year PFS and LRC than the interim PET-positive group (PFS: 70.6 % vs. 35.2 %, P = 0.025; LRC: 84.2 % vs 52.9, P = 0.046). In terms of (18)F-FDG PET/CT, ΔSUV13 on the final 18F-FDG PET/CT scan demonstrated better prediction (AUC of 0.812 for PFS, 0.807 for LRC, with a cutoff of 75 %; P = 0.016) than the parameters on pre and interim scans. An SUVmax decrease ≥ 75 % on the final (18)F-FDG PET/CT scan was associated with better clinical outcome (PFS: 73.3 % vs. 36.8 %, P = 0.022; LRC: 86.7 % vs 52.6, P = 0.029). These correlations were most prominent in the subgroup of patients treated with chemoradiotherapy.ConclusionEarly interim (18)F-FLT PET/CT is a significant predictor of 2-year PFS and LRC, which is correlated better with early responses and late outcomes than interim (18)F-FDG PET/CT in esophageal squamous cancer patients.

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