Noncardia gastric cancer on the rise among younger U.S. whites

Last Updated: 2018-01-26

By Will Boggs MD

NEW YORK (Reuters Health) - Rates of noncardia gastric cancer are increasing among U.S. non-Hispanic whites age 50 or younger, according to results from 45 North American Association of Central Cancer Registries (NAACCR).

"We were surprised to learn that rising noncardia stomach cancer rates among younger generations were mainly restricted to counties with less than 20% prevalence of poverty, suggesting that factors other than H. pylori infection, which is relatively less common among affluent areas, may be driving these trends," Dr. M. Constanza Camargo from the National Cancer Institute, in Bethesda, Maryland, told Reuters Health by email.

Unlike cardia (upper stomach) tumors, which start with damage from acid reflux and/or metabolic syndrome, noncardia (lower stomach) tumors follow nonatrophic gastritis and a sequence of increasingly severe mucosal lesions, typically associated with chronic H. pylori infection or autoimmune gastritis.

Dr. Camargo's team used NAACCR data from 1995 to 2013 to explore associations of shifting risk factors with U.S. noncardia gastric cancer incidence. They found more than 137,000 noncardia cancers in 4.4 billion person-years of observation.

Most of these cancers occurred among non-Hispanic whites, individuals age 50 or older at diagnosis, and in counties with poverty rates of less than 20%.

Overall age-standardized rates (ASRs) per 100,000 person-years were 2.2 for non-Hispanic whites, 6.4 for non-Hispanic blacks, 6.2 for Hispanics and 7.7 for other non-Hispanics, the researchers report in the Journal of the National Cancer Institute, online January 19.

ASRs declined by an average 3.0% per year overall, whereas incidence rates increased 1.3% annually among non-Hispanic whites younger than age 50 while decreasing 2.6% annually among older non-Hispanic whites.

This trend was most pronounced among non-Hispanic white women, whose incidence rates increased by 2.6% annually for those younger than 50 and decreased 2.2% annually for those age 50 or older.

If these trends continue, noncardia cancer incidence among women is expected to surpass that among men by around 2025, the researchers say.

This would reverse the classic disease pattern of being twice as common in men as in women, according to Dr. Camargo.

Noncardia gastric cancer in Hispanics showed a similar pattern, with slightly rising rates for individuals younger than 50 versus falling rates for individuals age 50 or older.

In contrast, incidence trends for noncardia gastric cancer declined for non-Hispanic blacks and non-Hispanic others, regardless of age.

"Although our research work was a descriptive study, not one designed to evaluate causality, several of our findings invite speculation on the role of antibiotic use in rising noncardia stomach cancer incidence among younger generations," Dr. Camargo said. "Antibiotic medications were introduced into standard medical practice in the 1950s and have been increasing ever since, which is consistent with the falling rates for those born before 1951 and rising rates for those born after 1951. Use of antibiotic medications can disrupt the native microbiome of the stomach, and may lead to autoimmune gastritis, one of the causes of noncardia stomach cancer."

Dr. Martin J. Blaser from New York University Langone Medical Center, New York, who coauthored a linked editorial, told Reuters Health by email, "This work identified what appears to be a 'new' cancer, that has arisen since World War II, and predominantly affects relatively young people (under 50). With the disappearance of H. pylori, gastric cancer was supposed to go away, but this is a very disturbing trend."

"And the biology has shifted - gastric cancer has historically affected men more than women, but for this new cancer, women seem to be at greater risk, and the rate of increase is substantial," he said.

"One important message is that we have been in an era of changes in the human microbiome," Dr. Blaser said. "This is quite clear with the disappearance of H. pylori. This new cancer provides evidence that this might not be a panacea (despite doctors everywhere trying to eradicate the organism). We need to better understand our relationship with our ancient (ancestral) microbes, so we can optimize health across the population."

"Doctors must begin to think about gastric cancer in people in their 40s and younger," he said. "Gastric cancer is very difficult to treat, so new approaches should be found (since the years of life lost are substantial). Right now, the numbers are relatively small, but they have been growing."

SOURCES: http://bit.ly/2ncV1O4 and http://bit.ly/2BuKfrA

J Natl Cancer Inst 2018.