Clinicopathological Features of Early Gastric Cancer Complicated by Autoimmune Gastritis

Background: In the post-Helicobacter pylori era, autoimmune gastritis (AIG) is attracting increasing attention as an origin of gastric cancer. Here, we performed clinicopathological examination of gastric cancer complicating AIG treated in our hospital. Methods: Eight-six early gastric cancer lesions complicating AIG in 50 patients were treated by endoscopic submucosal dissection (ESD) at our hospital in 2008-2022. Their clinicopathological characteristics were compared with those of a control group comprising 2978 early gastric cancer lesions (excluding lesions in the remnant stomach after surgery) in 2278 patients treated by ESD during the same period. Results: Mean age was significantly higher in the AIG group than in the control group (74.7 years vs 70.9 years; p<0.01). In the respective groups, the occurrence rate of synchronous/metachronous lesions was 38.0% and 20.4% (p<0.01), the ratio of longitudinal cancer locations (upper/middle/lower third [U/M/L]) was 27/32/27 and 518/993/1467 (p<0.01), the ratio of circumferential cancer locations (lesser curvature/greater curvature/anterior wall/posterior wall) was 25/31/12/18 and 1259/587/475/657 (p<0.01), the ratio of major macroscopic types (I/IIa/IIb/IIc) was 13/38/5/30 and 65/881/220/1812 (p<0.01). The rates of multiple gastric cancer and cancers in the U region, at the greater curvature, and of protruding types were significantly higher in the AIG group. Conclusion: The occurrence rate of multiple gastric cancer was significantly higher in gastric cancer complicating AIG (approximately 40%), and compared with the control group, the proportions of cancers at the U region, at the greater curvature, and of protruding types were significantly higher.