.Abstract
PURPOSE: Parameters of positron emission tomography-computed tomography (PET-CT) were compared with the results of histopathologic examination in order to determine which can provide an objective indication of response after neoadjuvant chemoradiation for treatment of thoracic esophageal squamous cell carcinoma (SCC).

MATERIALS AND METHODS: Between August 2003 and January 2010, data on 25 patients who underwent neoadjuvant chemoradiation and subsequent resection for treatment of esophageal SCC were retrospectively reviewed. Changes in maximum standardized uptake value (ΔSUVmax), metabolic tumor volume (ΔMTV), and total lesion glycolysis (ΔTLG) were analyzed by comparison with the histopathologic findings.

RESULTS: Pathologic complete remission (CR) for the main tumor was achieved in 11 patients. Postradiation esophagitis was observed in 10 patients. ΔSUVmax of the main tumor was significantly greater in the CR group than in the partial response (PR) group (p=0.039), while ΔMTV and ΔTLG of the main tumor were not (p=0.141 and p=0.349, respectively). The cut-off ΔSUVmax value for CR was estimated as 72.1%, indicating significantly better accuracy than visual interpretation (p=0.045). Of the 48 involved lymph nodes, ΔSUVmax and ΔMTV of lymph nodes were significantly greater in the CR group than in the PR group (p=0.045 and p=0.014, respectively), while ΔTLG was not (p=0.063). The cut-off value of ΔSUVmax for prediction of CR in lymph nodes was calculated as 50.67%.

CONCLUSION: PET-CT could be used for prediction of response to neoadjuvant treatment in thoracic esophageal SCC. ΔSUVmax may be a more significant predictor for CR after neoadjuvant chemoradiation than ΔTLG and ΔMTV.