Endoscopic submucosal dissection for papillary adenocarcinoma of the stomach: low curative resection rate but favorable long-term outcomes after curative resection.

BACKGROUND: The previous studies demonstrated aggressive clinicopathologic features of papillary early gastric cancer (EGC). This raised concerns about the appropriateness of current Japanese guidelines that recommend the same endoscopic submucosal dissection (ESD) criteria for papillary EGC as for well-differentiated (WD) or moderately differentiated (MD) EGCs.
METHODS: This study included 4140 patients who underwent ESD for differentiated-type EGC (87 papillary EGCs and 4259 WD or MD EGCs). The clinicopathologic characteristics and short- and long-term outcomes of ESD for papillary EGC were reviewed and compared with those for WD or MD EGC.
RESULTS: Papillary EGCs were larger, and had higher lymphovascular and submucosal invasion rates than WD or MD EGCs. Lateral resection margin involvement and histological heterogeneity were found more frequently in papillary EGC than in WD or MD EGC. En bloc with R0 resection and curative resection rates of papillary EGC were 85.1 and 49.4%, respectively, and both were significantly lower than those of WD or MD EGC (93.0 and 82.2%). In mucosal cancers, curative resection rates of papillary EGC and WD or MD EGC were 72.5 and 93.7%, respectively. Among patients undergoing curative ESD for papillary EGC, no extra-gastric recurrences occurred during median 58 months of follow-up. Metachronous recurrence occurred in 5.2% of cases.
CONCLUSIONS: Given the favorable long-term outcomes after curative resection, ESD might be indicated for papillary EGC according to the current Japanese guidelines. As papillary EGC has considerable lymphovascular and submucosal invasion rates, careful histological examination is required to accurately determine whether curative ESD is achieved.