• Jurriën Stiekema, Daan Vermeulen, Erik Vegt, Francine E M Voncken, Berthe M P Aleman, Joyce Sanders, Henk Boot, and Johanna W van Sandick.
• From the Departments of *Surgery, †Nuclear Medicine, ‡Radiation Oncology, §Pathology, and ¶Gastroenterology and Hepatology, The Netherlands Cancer Institute, Amsterdam, the Netherlands.
• Clin Nucl Med. 2014 Oct 1; 39 (10): 862-7.

AimThe aim of this study is to evaluate the potential of FDG PET/CT for the detection of interval distant metastases after neoadjuvant chemoradiotherapy (CRT) and the prediction of the pathologic response to CRT in esophageal cancer patients.Patients And MethodsIn this retrospective study, all esophageal cancer patients for whom CRT followed by surgery was planned between January 2008 and April 2013 and in whom an FDG PET/CT was performed before and after CRT were included. For the response analyses, both FDG PET/CT scans had to be made on a similar scanner. Metabolic response of the primary tumor was assessed using the SUVmax, metabolic tumor volume (MTV), and total lesion glycolysis (TLG). These parameters were correlated with the pathologic response using the tumor regression grade (TRG) scale according to Mandard et al (Cancer. 1994;73:2680-2686).ResultsIn 6 (8%) of 76 consecutively treated patients, new distant metastases were detected on FDG PET/CT after neoadjuvant CRT; these patients therefore did not undergo operation. Forty-eight (63%) of 76 patients were eligible for response analysis. The relative change in SUVmax, MTV, and TLG was significantly different between patients with a major (TRG, 1-2) and a minor response (TRG, 3-5) but not between patients with and without a pathologic complete response. The area under the curve of the receiver operating characteristic for predicting a major response was 0.70 (95% confidence interval, 0.65-0.92) for a relative decrease in SUVmax, compared with 0.73 (95% confidence interval, 0.58-0.88) both for MTV and TLG. A relative decrease in SUVmax of 60% or more had the highest positive predictive value (75%).ConclusionsFutile surgery was prevented in 8% of our esophageal cancer patients because interval metastases were detected on an FDG PET/CT after neoadjuvant CRT. The accuracy for predicting a complete or major pathologic response was limited and does not support the use of FDG PET/CT for refraining from surgical treatment.

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