Diagnostic accuracy of EUS in differentiating mucosal versus submucosal invasion of superficial esophageal cancers: A systematic review and meta-analysis

Background: The prognosis of esophageal cancer (EC) depends on the depth of tumor invasion and lymph node metastasis. EC limited to the mucosa (T1a) can be treated effectively with minimally invasive endoscopic therapy, whereas submucosal (T1b) EC carries relatively high risk of lymph node metastasis and requires surgical resection. Objective: To determine the diagnostic accuracy of EUS in differentiating T1a EC from T1b EC. Design: We performed a comprehensive search of MEDLINE, SCOPUS, Cochrane, and CINAHL Plus databases to identify studies in which results of EUS-based staging of EC were compared with the results of histopathology of EMR or surgically resected esophageal lesions. DerSimonian-Laird random-effects model was used to estimate the pooled sensitivity, specificity, and likelihood ratio, and a summary receiver operating characteristic (SROC) curve was created. Setting: Meta-analysis of 19 international studies. Patients: Total of 1019 patients with superficial EC (SEC). Interventions: EUS and EMR or surgical resection of SEC. Main Outcome Measurements: Sensitivity and specificity of EUS in accurately staging SEC. Results: The pooled sensitivity, specificity, and positive and negative likelihood ratio of EUS for T1a staging were 0.85 (95% CI, 0.82-0.88), 0.87 (95% CI, 0.84-0.90), 6.62 (95% CI, 3.61-12.12), and 0.20 (95% CI, 0.14-0.30), respectively. For T1b staging, these results were 0.86 (95% CI, 0.82-0.89), 0.86 (95% CI, 0.83-0.89), 5.13 (95% CI, 3.36-7.82), and 0.17 (95% CI, 0.09-0.30), respectively. The area under the curve was at least 0.93 for both mucosal and submucosal lesions. Limitations: Heterogeneity was present among the studies. Conclusion: Overall EUS has good accuracy (area under the curve <0.93) in staging SECs. Heterogeneity among the included studies suggests that multiple factors including the location and type of lesion, method and frequency of EUS probe, and the experience of the endosonographer can affect the diagnostic accuracy of EUS.