Multimodal Imaging of Pathologic Response to Chemoradiation in Esophageal Cancer

Publication date: Available online 2 March 2018
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Penny Fang, Benjamin C. Musall, Jong Bum Son, Amy C. Moreno, Brian P. Hobbs, Brett W. Carter, Bryan M. Fellman, Osama Mawlawi, Jingfei Ma, Steven H. Lin
PurposeTo examine the value of early changes in quantitative diffusion-weighted imaging (DWI) and ¹⁸F-deoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for discriminating complete pathologic response (pCR) to chemoradiation (CRT) in esophageal cancer.MethodsTwenty esophageal cancer patients treated with chemoradiation followed by surgery were prospectively enrolled. Patients underwent MRI and FDG-PET/CT scans at baseline (BL), interim (IM, 2 weeks after CRT start), and first follow-up (FU). Based on pathologic findings at surgery, patients were categorized into tumor regression groups (TRG1, TRG2, and TRG3+). Distributions of summary statistics in apparent diffusion coefficient (ADC) and FDG-PET at BL and relative change at IM and FU scans were compared between pCR/TRG1 and non-pCR/TRG2+ groups and across readers. Receiver operating characteristics (ROCs) were evaluated for summary measures to characterize discrimination of pCR from non-pCR.ResultsRelative changes in tumor volume ADC (ΔADC) mean, 25^th and 10^th percentiles were able to completely discriminate (AUC=1, p<0.0011) between pCR and non-pCR (thresholds = 27.7%, 29.2%, and 32.1%, respectively) and were found to have high inter-reader reliability (95% limits of agreement of 1.001, 0.944 and 0.940, respectively). Relative change in total lesion glycolysis (TLG) from BL to IM was significantly different among pCR and non-pCR groups (p=0.0117) and yielded AUC of 0.947 (95% CI: 0.8505-1.043). An optimal threshold of 59% decrease in TLG provided optimal sensitivity (specificity) of 1.000 (0.867). Changes in ADC summary measures were negatively correlated with that of TLG (Spearman, -0.495, p=0.027).ConclusionQuantitative volume ΔADC and TLG during treatment may serve as early imaging biomarkers for discriminating pathologic response to chemoradiation in esophageal cancer. Validation of this data in larger prospective multicenter studies is essential.



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