The role of tumor size in surgical decision making after endoscopic resection for early gastric cancer

Background: Endoscopic resection (ER) is curative treatment option for early gastric cancer (EGC). Additional surgery is required when the tumor pathology is beyond ER indication. It is unclear whether tumor size can be correlated with indications for surgery after ER. Therefore, we aimed to access the role of tumor size for surgical decision making after ER. Methods: We reviewed clinicopathological data from 3246 patients underwent gastrectomy for EGC. The patients were classified into three groups as follows: the ulcer-negative intramucosal cancer with undifferentiated histology, ulcerative intramucosal cancer with differentiated histology, and minute submucosal (SM1) cancer with differentiated histology. The probability of additional surgery after ER was defined as at least one positive result for lymph node metastasis, lymphovascular invasion or perineural invasion. The probability was compared between individual tumor size and ER size criteria in each group using area under receiver operating characteristic curves. Results: The probabilities of ulcer-negative intramucosal cancer with undifferentiated histology, SM1 cancer with differentiated histology and ulcerative intramucosal cancer with differentiated histology were 4.2, 22.1 and 2.5 %. In the ulcerative intramucosal cancer with differentiated histology group, these probabilities increased when the difference in tumor size was >1 mm compared with ER size criteria. The probability was not increased when there was a >10-mm tumor size difference compared with ER size criteria in the other two groups. Conclusions: Tumor size was correlated with ER criteria in patients with ulcerative intramucosal cancer with differentiated histology after ER but was not strictly correlated with ER criteria in the other two patient groups. However, further study may be necessary to validate our results in the future.