RT Journal Article SR Electronic T1 Surveillance of Clinically Complete Responders Using Serial 18F-FDG PET/CT Scans in Patients with Esophageal Cancer After Neoadjuvant Chemoradiotherapy JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 486 OP 492 DO 10.2967/jnumed.120.247981 VO 62 IS 4 A1 Maria J. Valkema A1 Berend J. van der Wilk A1 Ben M. Eyck A1 Bas P.L. Wijnhoven A1 Manon C.W. Spaander A1 Michail Doukas A1 Sjoerd M. Lagarde A1 Wendy M.J. Schreurs A1 Mark J. Roef A1 J. Jan B. van Lanschot A1 Roelf Valkema YR 2021 UL http://jnm.snmjournals.org/content/62/4/486.abstract AB Active surveillance for patients with esophageal cancer and a clinically complete response (cCR) after neoadjuvant chemoradiotherapy (nCRT) is being studied. Active surveillance requires accurate clinical response evaluations. 18F-FDG PET/CT might be able to detect local tumor recurrence after nCRT as soon as the esophagus recovers from radiation-induced esophagitis. The aims of this study were to assess the value of serial 18F-FDG PET/CT scans for detecting local recurrence in patients beyond 3 mo after nCRT and to determine when radiation-induced esophagitis has resolved. Methods: This retrospective multicenter study included patients who had cCR after nCRT, who initially declined surgery, and who subsequently underwent active surveillance. Clinical response evaluations included 18F-FDG PET/CT, endoscopic biopsies, and endoscopic ultrasound with fine-needle aspiration at regular intervals. SUVmax normalized for lean body mass (SULmax) was measured at the primary tumor site. The percentage change in SULmax (Δ%SULmax) between the last follow-up scan and the scan at 3 mo after nCRT was calculated. Tumor recurrence was defined as biopsy-proven vital tumor at the initial tumor site. Results: Of 41 eligible patients, 24 patients had recurrent disease at a median of 6.5 mo after nCRT and 17 patients remained cancer free during a median follow-up of 24 mo after nCRT. Five of 24 patients with tumor recurrence had sudden intense SULmax increases of greater than 180%. In 19 of 24 patients with tumor recurrence, SULmax gradually increased (median Δ%SULmax, +18%), whereas SULmax decreased (median Δ%SULmax, −12%) in patients with ongoing cCR (P < 0.001, independent-samples t test). In patients with ongoing cCR, SULmax was lowest at 11 mo after nCRT. Conclusion: Serial 18F-FDG PET/CT might be a useful tool for detecting tumor recurrence during active surveillance. In patients with ongoing cCR, the lowest SULmax was reached at 11 mo after nCRT, suggesting that radiation-induced esophagitis had mostly resolved by that time. These findings warrant further evaluation in a larger cohort.