Diverging Trends in the Incidence of Reflux-related and Helicobacter pylori-related Gastric Cardia Cancer

Goals: To describe historical incidence trends of 2 subtypes of gastric cardia cancer. Background: The incidence of gastric cardia cancer has increased in western countries. Prior studies have treated cardia cancer as a single entity, but recent data suggest that there are 2 distinct subtypes: reflux-related and Helicobacter pylori-related. Study: We conducted a population-based study using Connecticut Tumor Registry data from 1955 to 2007. Age-adjusted incidence rates (per 100,000 person-years) were calculated for gastric cancer, as a whole and by anatomic subsite, and for esophageal adenocarcinoma. Cardia and noncardia cancer incidence rates were further adjusted to account for cases with unspecified subsite. Mathematical formulas were derived to calculate incidence rates for reflux-related and H. pylori-related cardia cancer. Results: The adjusted incidence of cardia cancer was 4.0 per 100,000 in 1955 to 1959, decreased to 2.4 per 100,000 in 1965 to 1969 before increasing to 3.4 per 100,000 by 2003 to 2007. The incidence of H. pylori-related cardia cancer decreased from 3.7 to 1.0 per 100,000 over the study period, whereas reflux-related cardia cancer increased progressively from 0.3 to 2.4 per 100,000. The curves for reflux-related cardia cancer and esophageal adenocarcinoma closely mirrored each other, and their combined incidence increased from 0.5 per 100,000 in 1955 to 1959 to 5.6 per 100,000 in 2003 to 2007. Conclusions: The incidence of reflux-related cardia cancer has steadily increased, whereas H. pylori-related cardia cancer has declined progressively since the mid-20th century. Trends in reflux-related cardia cancer and esophageal adenocarcinoma incidence are very similar, suggesting that these 2 cancers share a similar etiology and pathophysiological process.