FA06.05: DETECTING RESIDUAL ESOPHAGEAL CANCER AFTER NEOADJUVANT CHEMORADIATION BY ENDOSCOPIC BIOPSIES, EUS AND FDG-PET: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background After curatively intended neoadjuvant chemoradiotherapy (nCRT) according to CROSS plus surgery for esophageal cancer, 29% of patients have a pathologic complete response. Active surveillance after nCRT, in which patients undergo frequent clinical examinations and where esophagectomy is only offered to those with a locoregional regrowth without distant metastases, has been proposed as novel treatment option. This study provides a systematic review and meta-analysis of the literature regarding the accuracy of endoscopic biopsies, endoscopic ultrasound (EUS) and 18F-FDG PET(-CT) for detecting residual disease after nCRT for esophageal cancer. Methods A systematic literature search in Embase, Medline, Cochrane and Web of Science was performed. Two reviewers independently collected studies on the diagnostic accuracy of endoscopic biopsies, EUS and 18F-FDG PET(-CT) for detecting residual disease after nCRT at the primary tumor site or in regional lymph nodes for potentially curable esophageal adenocarcinoma (AC) or squamous cell carcinoma (SCC). Histopathological examination of the resection specimen was the reference standard. Study quality was appraised with the QUADAS-2 tool. Sensitivity and specificity values were calculated and pooled using meta-analyses. Subgroup analyses were performed to investigate possible sources of heterogeneity. Results 60 studies were included for qualitative analysis and 40 for quantitative analysis. For detecting residual disease at the primary tumor site, 11 studies evaluated endoscopic biopsies, 11 described EUS qualitatively, 14 evaluated PET qualitatively, 12 evaluated PET quantitatively, 6 of them using SUVmax and 6 of them using DSUVmax. Summary sensitivity values were 0.36 (95%CI 0.27–0.45), 0.97 (95%CI 0.94–0.98), 0.74 (95%CI 0.66–0.81), 0.68 (95%CI 0.61–0.74) and 0.68 (95%CI 0.54–0.79), respectively. Summary specificity values were 0.93 (95%CI 0.85–0.97), 0.09 (95%CI 0.04–0.19), 0.52 (95%CI 0.40–0.63), 0.70 (95%CI 0.61–0.78), 0.70 (95%CI 0.60–0.78) and respectively. For detecting residual malignant lymph nodes, 11 studies evaluated EUS with a summary sensitivity of 0.68 (95%CI 0.54–0.80) and a summary specificity of 0.58 (95%CI 0.45–0.70). Subgroup analyses demonstrated that sensitivity of endoscopic biopsy, PET DSUVmax and EUS for nodal was higher in SCC than in AC. Conclusion Current literature suggests insufficient accuracy of endoscopic biopsies, EUS and 18F-FDG PET(-CT) as individual modalities for detecting residual disease after nCRT for potentially curable esophageal cancer. Disclosure All authors have declared no conflicts of interest.