Undifferentiated histology is associated with missed gastric cancer in individuals with prior Helicobacter pylori eradication undergoing screening endoscopy

This study aimed to identify tumor lesion-related factors associated with possible missed gastric cancer (PMGC) during screening endoscopy, with particular focus on cases following Helicobacter pylori (HP) eradication. We analyzed consecutive gastric cancer (GC) cases detected at 11 health check-up institutions in Akita prefecture, Japan. The study focused on 171 GC cases with at least one negative endoscopy within the preceding 2 years. Based on histological assessment, GCs with pT1b or deeper invasion were classified as PMGCs. Their clinical characteristics were compared with those of the remaining pT1a GCs. A backward stepwise logistic regression analysis was performed to identify tumor lesion-related factors associated with PMGC. Among 171 GC cases, 39 (22.8%) were classified as PMGC, while the remaining 132 served as controls. Overall, 108 cases (63.2%) occurred in individuals with prior HP eradication, and eradication status was not statistically associated with PMGC. Multivariable regression analysis limited to post-eradication cases revealed that upper third location and undifferentiated histology were significantly associated with PMGC, with odds ratios (95% confidence intervals) of 5.65 (1.88-16.90) and 8.35 (2.22-31.40), respectively. Undifferentiated histology and upper third location were associated with missed diagnoses of GC during screening endoscopy in individuals with prior HP eradication. These findings are clinically relevant for improving the quality of endoscopic examinations in health check-up settings, especially given the increasing prevalence of post-eradication GC.