Increased incidence of metachronous gastric neoplasm after endoscopic resection in patients with synchronous gastric neoplasm

Background: Recurrence risk is a major concern after endoscopic resection (ER) of gastric neoplasms. This study was to compare metachronous risk in patients with and without synchronous neoplasms after complete ER. Methods: After ER for gastric neoplasms, patients were divided into those with and without synchronous neoplasm. The metachronous risk of gastric neoplasms was compared between the two groups. Results: After ER of 678 cancers and 891 adenomas, synchronous neoplasm was found in 11.8% of cancers and 11.4% of adenomas. In the multiple (n = 182) and the single group (n = 1387), metachronous neoplasms occurred in 18.1 and 8.6%, respectively (HR 2.40; 95% CI, 1.62-3.34). When the pathology of the recurred lesion was limited to cancer, metachronous risk was also significantly higher in the multiple than in the single group (HR, 2.2; 95% CI, 1.17-3.85). In the recurred pathology of the multiple group, cancer development was frequently observed in patients with cancer compared to those with only adenomas in the synchronous lesion (67.0% vs. 13.0%, respectively; P = 0.023). Conclusions: This study demonstrated that metachronous risk was significantly higher in patients with synchronous gastric neoplasms after ER. Therefore, meticulous examination is important in patients with synchronous neoplasm.