Endoscopic Diagnosis of Early Gastric Cancer

Gastric cancer is the fifth most common malignancy and the third leading cause of cancer death worldwide in 2018 [1]. More than one million cases of gastric cancer newly occurred in a year (1,033,701 cases in 2018) [1]. Early gastric cancer was defined by The Japanese Society of Gastroenterological Endoscopy in 1962 as an adenocarcinoma confined to the mucosa or submucosa regardless of the lymph node metastasis. A 5-year survival rate of the patients who underwent gastrectomy with lymph node dissection for early gastric cancer was over 95% [2]. The rate of lymph node metastasis of intramucosal gastric cancer is less than 3% [3, 4], and it is practically 0% when it fulfills the following histopathological characteristics: ≤2 cm in size, differentiated type, and absence of ulcerative findings (UL) [4]. Moreover, the expanded indication for endoscopic resection have been confirmed to have a sufficient therapeutic effect [5]. Thus, early gastric cancer is expected to have a favorable prognosis if proper treatment is given.