Submucosal saline injection followed by endoscopic ultrasound versus endoscopic ultrasound only for distinguishing between T1a and T1b esophageal cancer

Purpose: To examine whether submucosal saline injection (SSI) can improve traditional endoscopic ultrasound9s (EUS) accuracy in distinguishing between T1a and T1b stage esophageal squamous cell carcinoma (ESCC). Experimental Design: 180 T1N0M0 stage ESCC patients aged 18-85 years old were enrolled between February 14, 2012 to June 4, 2018 at Sun Yat-sen University Cancer Center in China. They were randomly assigned (1:1) to receive either EUS examination after 3-5 ml submucosal saline injection (SSI) or EUS only examination. All the patients were referred to thoracic surgeons to receive endoscopic resection (ER) or esophagectomy 5-10 days after EUS examination. Standard EUS criteria were used to preoperatively stage the ESCC cases, while surgical pathology reports after referral were used to postoperatively stage the cases. The primary endpoint was the diagnostic accuracy of T1b staging (defined as the sum of the true positive [T1b] and true negative [T1a] cases divided by the total number of cases). Results: Among the per-protocol population, SSI+EUS group (n=81) was superior to the EUS-only group (n=85) in terms of the diagnostic accuracy for T1b staging (93.8% [95% CI, 88.6-99.1] vs. 65.9% [95% CI, 55.8-76.0]; P<0.001). The positive predictive value of SSI+EUS for diagnosing T1b ESCC reached 90.9% (95%CI, 81.1-100), which was significantly superior to that of EUS only (0.576 [0.450-0.702], P=0.001). Conclusions: SSI significantly improves the diagnostic accuracy of EUS in distinguishing between T1a and T1b ESCC, which might help avoid unnecessary esophagectomy and diagnostic ER.