Gastric cancer inversely associated with esophageal adenocarcinoma

Last Updated: 2016-01-27

By Will Boggs MD

NEW YORK (Reuters Health) - The incidences of gastric cancer and esophageal adenocarcinoma (EAC) are inversely related, suggesting a common environmental factor that exerts opposite effects on these cancers, researchers from the U.K. report.

"Esophageal adenocarcinoma and gastric cancer occur very close to each other in the upper gastrointestinal tract and are very similar histologically under the microscope," Dr. Kenneth E. L. McColl from the University of Glasgow told Reuters Health by email. "It was therefore very surprising that one should be showing a marked fall in incidence and the other a marked rise in the incidence over similar time periods."

Opposing trends for the incidence of EAC and noncardia gastric cancer (NCGC) have been previously reported in the East of England, Dr. McColl and colleagues note in The American Journal of Gastroenterology, online January 12.

The team examined the relationship between the current incidences and the changes in incidence over time for the two cancers in 51 different countries using data from Cancer Incidence in Five Continents Vol. X (CI5X) and GLOBOCAN 2012.

The incidence of EAC ranged from 0.23 to 7.24 per 100,000 person-years; that of total gastric cancer (TGC) varied from 2.84 to 62.26, and the incidence of NCGC varied from 1.75 to 58.64, with the highest gastric cancer incidence in East Asia and the lowest gastric cancer incidence in Western Europe and North America. EAC showed the opposite trend.

There were significant negative correlations between the incidence rates of EAC and both TGC and NCGC, the researchers found.

A longitudinal study of 38 populations showed a significant decrease in the incidence of TGC along with a significant increase in the incidence of EAC between 1989 and 2007.

Significant negative correlations between incidence rate trends of EAC and TGC over time were evident in 27 of the 38 populations when compared over the previous 19-50 years.

"The fact that they are both changing indicates that they are being influenced by changes in environmental factors," Dr. McColl explained. "One therefore has to ask what change in environmental factor could have such opposite effects on their incidences. The likeliest candidate is H. pylori infection as that is known to be the most important acquired factor in the cause of gastric cancer and also epidemiological studies have shown a marked inverse association between the infection and esophageal adenocarcinoma."

"There is also a possible mechanism by which the infection could exert these opposite effects," Dr. McColl explained. "The infection, which is very common in the general population, damages the lining of the stomach and this is thought to lead to gastric cancer. However, the damaging of the lining of the stomach also reduces the ability of the stomach to secrete acid and this may protect from esophageal adenocarcinoma as it is induced by acid reflux from the stomach into the gullet."

SOURCE: bit.ly/1SiR9oF

Am J Gastroenterol 2016.