Detecting pathological complete response in esophageal cancer after neoadjuvant therapy based on imaging techniques: a diagnostic systematic review and meta-analysis

Abstract Background Up to 32% of patients with esophageal cancer show a pathological complete response (ypCR) after neoadjuvant therapy. In order to prevent overtreatment, the indication to perform esophagectomy in these patients should be reconsidered. Implementing an organ preserving strategy for patients with ypCR requires an accurate assessment of residual disease after neoadjuvant treatment. The aim of this study was to systematically review the effectiveness of imaging techniques used for detection of ypCR after neoadjuvant therapy but prior to resection in patients with esophageal cancer. Methods A systematic literature search of Medline, Embase and Cochrane Library databases was performed from 1 January 2000 to 13 December 2017. Eligible studies were diagnostic studies which compared results of imaging modalities after neoadjuvant therapy to histopathological findings in the resection specimen after esophagectomy. Methodological quality was assessed by the Cochrane QUADAS-2 model. Primary outcome measures were true positive, false positive, false negative and true negative values of imaging techniques predicting ypCR. A meta-analysis was performed by pooling sensitivities and specificities using a bivariate model. Results A total of 4420 articles were identified. After exclusion of irrelevant titles and abstracts, 360 articles were reviewed in full text. In total 4 imaging modalities (CT, PET-CT, EUS and MRI) were used for restaging. The meta-analysis was conducted with data from 56 studies involving 3625 patients. The pooled sensitivity of CT, PET-CT, EUS and MRI for detecting ypCR was 0.35, 0.62, 0.01 and 0.80, whereas the pooled specificity was 0.83, 0.73, 0.99 and 0.83, respectively. The positive predictive value in detecting ypCR was 0.47 for CT, 0.41 for PET-CT, not applicable for EUS and 0.61 for MRI. Conclusion Current imaging modalities like CT, PET-CT and EUS seem to be insufficiently accurate to identify complete responders. More accurate diagnostic tests are needed to improve restaging accuracy for patients with esophageal cancer.