Assessment of response to neoadjuvant therapy in esophageal cancer: an updated systematic review of diagnostic accuracy of endoscopic ultrasonography and fluorodeoxyglucose positron emission tomography.

For assessing response to neoadjuvant therapy in patients with esophageal cancer, both endoscopic ultrasonography (EUS) and fluorodeoxyglucose positron emission tomography (FDG-PET) are commonly used, and despite few controlled trials, it is not known if one imaging modality is superior to the other. Also, relative diagnostic accuracy of early (during the course of neoadjuvant therapy) and FDG-PET after completion of neoadjuvant therapy has not been reviewed. The aim of this study was to perform a systematic review of published information to compare diagnostic accuracy of EUS and FDG-PET in this setting. A search of the MEDLINE, EMBASE, and Cochrane databases was performed along with a manual search of cross-references of eligible articles. Data on the accuracy of the imaging modalities were compared by constructing summary receiver-operating characteristic curves. Seven studies with EUS and 15 with FDG-PET were included in the final analysis (N= 966). The sensitivity of EUS and FDG-PET ranged from 20 to 100% and 42 to 100%, respectively. The specificity ranged from 36 to 100% and 27 to 100%, respectively. The areas under the curve were 0.86 (95% confidence interval [CI]: 0.77-0.96) for EUS and 0.80 (95% CI: 0.72-0.89) for FDG PET (P= 0.37). The maximum joint sensitivity and specificity (Q* index) values for EUS and FDG-PET were 0.79 (95% CI: 0.70-0.88) and 0.74 (95% CI: 0.66-0.81), respectively (P= 0.38). There was no difference in accuracy between early FDG-PET and FDG-PET after completion of neoadjuvant therapy. EUS and FDG-PET have similar overall diagnostic accuracy for assessment of response to neoadjuvant therapy in patients with esophageal cancer.