Incidental detection of cancers during population-based endoscopic gastric cancer screening in Japan

Upper gastrointestinal endoscopy traverses the full upper aerodigestive tract, unlike radiography, potentially enabling incidental detection of non-gastric malignancies. However, its population-level incidental detection rate for non-gastric upper aerodigestive tract cancers has not been systematically quantified. The aim of this study was to compare endoscopic screening with radiography and quantify detection of non-gastric upper aerodigestive tract cancers in a population-based setting.

This population-based cohort study was conducted by linking the Okayama City municipal gastric cancer screening registry with the Kokuho Database (KDB) for fiscal years 2016-2021. Among 36,326 participants contributing 64,822 screening examinations (40,832 radiography; 23,990 endoscopy), diagnoses of oral cavity, pharyngeal, laryngeal, and esophageal cancer occurring within 2 months of screening were ascertained from the KDB. Generalized estimating equations with modified Poisson regression were used to estimate adjusted risk ratios (aRRs) comparing endoscopy with radiography.

Endoscopic screening was significantly associated with higher composite incidental detection rates for non-gastric upper aerodigestive tract cancers (95.9 vs. 34.3 per 100,000 examinations; aRR 2.94, 95% confidence interval [CI] 1.50-5.76; p = 0.002). Specifically, esophageal cancer detection was markedly higher with endoscopy (83.4 vs. 17.1 per 100,000; aRR 5.16, 95% CI 2.16-12.32; p < 0.001). No statistically significant differences were observed for oral cavity, pharyngeal, or laryngeal cancers.

Endoscopic gastric cancer screening is associated with substantially higher incidental detection of non-gastric upper aerodigestive tract cancers, particularly esophageal cancer. These findings suggest an additional detection value for endoscopy that extends beyond its primary gastric cancer target in organized screening programs.