Magnifying Endoscopy With Narrow Band Imaging Versus Endoscopic Ultrasonography for Prediction of Tumor Invasion Depth in Early Gastric Cancer: A Prospective Comparative Study

Overview

The treatment of early gastric cancer can be divided into endoscopic resection and surgery, and the precise staging of early gastric cancer is very important to prevent unnecessary surgery or additional surgery after the procedure. The possibility of endoscopic resection is determined by the risk of lymph node metastasis. The risk factors of lymph node metastasis of early gastric cancer are lesion size, presence of ulceration, histologic differentiation, and depth of invasion. In contrast to other factors, the factor of invasion depth is relatively difficult to predict by using the conventional white light endoscopy (WLE). Therefore, the endoscopic ultrasonography (EUS) has been tried to use for prediction of the invasion depth. However, many studies reported that the accuracy of endoscopic ultrasonography for predicting the depth of invasion was varied. A system consisting of a magnifying endoscope combined with narrow-band imaging (NBI), with the spectral band width narrowed by optical filters, was developed to enhance visualization of mucosal surface structure and vascular architecture. There were some reports that the magnifying endoscopy with narrow band imaging (ME-NBI) is superior to predict the histologic differentiation, depth of invasion and lesion margin than WLE. In this study, we divide the patients with suspected early gastric cancer (EGC) into the two groups as group using conventional WLE and EUS and group using WLE and ME-NBI, and try to compare the accuracy of EUS and ME-NBI for predicting the invasion depth of EGC. We also try to analyze the factors that affect the accuracy for predicting of depth such as characteristics of cancer lesion and histologic differentiation of cancer in each group. In addition, we try to analyze the characteristic imaging findings of ME-NBI for early gastric cancer and gastric adenoma and evaluate the efficacy of ME-NBI for early gastric cancer and gastric adenoma diagnosis.

The subjects is divided into early gastric cancer patients and gastric adenoma patients according to histologic biopsy result and white light endoscopic findings. Study 1 applies for early gastric cancer patients, Study 2 applies for gastric adenoma patients. A) Study 1 The NBI group performs ME-NBI first before EUS. The endoscopist evaluates NBI findings such as the invasion depth and describes ME-NBI impression. And then, EUS is performed likewise. The final treatment plan is determined by the EUS result, so group assignment does not affect the final treatment plan. The EUS group performs EUS first before NBI. The endoscopist evaluates EUS findings such as the invasion depth and describes EUS impression. And then, ME-NBI is performed likewise. The final treatment plan is determined by the EUS result, so group assignment does not affect the final treatment plan. According to clinical stage of early gastric cancer, endoscopic resection is performed in case of endoscopic resection indication or beyond indication but case of having the risk of surgery according to patient status. The surgical resection is performed if the patient wants surgery or does not meet the indications of endoscopic resection. The pathologist performs a histological evaluation of the resected gastric cancer lesion, including an invasive depth. B) Study 2 First, the endoscopist performs WLE and describes WLE findings and impression such as location, size, and gross morphology of lesion. The same examiner performs ME-NBI and describes ME-NBI findings and impression such as mucosal pattern, predicted degree of dysplasia. Endoscopic resection or surgical resection is performed according to the results of histologic result of gastric adenoma. The pathologist performs a histological evaluation of the resected dysplastic lesion.