Gastric cancer incidence rates highest in Asia

Last Updated: 2015-03-17

By Lisa Rapaport

NEW YORK (Reuters Health) - Gastric cancer rates are highest in eastern and southeastern Asia, according to a new analysis of age-adjusted incidence rates for different regions around the world.

"Our study described worldwide incidence patterns of gastric cancer subsites separately, providing new insights into the global burden of these cancers," lead study author Amy Colquhoun, a researcher at the University of Alberta, British Columbia, told Reuters Health by email. "This work will support future investigations across populations and aid planning and decision-making related to gastric cancer control strategies."

Colquhoun and colleagues used data from 290 cancer registries in 68 countries from 2003 to 2007 to assess the proportions of people with cardia gastric cancer (CGC) and non-CGC tumors, based on country, sex, and age groups older and younger than 65.

For countries with insufficient subgroup data, the researchers calculated regional proportions based on non-weighted, aggregated country-level data to estimate proportions of people with each type of gastric cancer.

In 2012, 952,000 cases of gastric cancer occurred globally, the researchers estimated, with two-thirds of cases in men and one-third in women, corresponding to global gastric cancer age-standardized incidence rates of 17.4 and 7.5 per 100,000, respectively.

Slightly more than one-fourth of the cases were CGC tumors, and more than half occurred in China. About 59% of these cases occurred in eastern and southeastern Asia. Another 15% of cases happened in central Asia, with 6% in central and South America and the Caribbean.

Almost two-thirds of non-CGC cases were in eastern and southeastern Asia, with more than half of these cases in China. Central Asia and Eastern Europe followed, each with approximately 8% of global cases.

While the exact reasons for the geographic differences are unknown, the researchers wrote in an article published online March 6 in Gut that higher-risk populations for CGC may have a high prevalence of risk factors such as obesity and gastroesophageal reflux disease, as well as Helicobacter pylori infections.

Consumption of foods high in salt may elevate the risk for non-GCG cases, the researchers wrote, noting that H pylori infections also make this type of stomach cancer more likely.

Estimated incidence "was limited by the extent to which topographical information identifying the exact location of gastric cancer cases was reported by each registry," and some data relied on surgical records to determine what type of malignancy was involved, the researchers noted.

"There are extreme national and regional variations in incidence and mortality for both types of gastric cancer, and we clearly don't understand the reasons for these variations because both tumors are associated with a complex combination of factors including helicobacter pylori, obesity, diet, the immune system, and genetics," Dr. Rolando Herrero, of the International Agency for Research on Cancer at the World Health Organization, told Reuters Health by email.

The different causes of the tumors can lead to different interventions for each type of gastric cancer, said Herrero, who wasn't involved in the study.

"While smoking control is likely to have an impact in reducing both types of tumors, treatment of helicobacter pylori infections and dietary interventions like reduction in salt consumption can be considered for non-CGC," he said. "For CGC, the potentially useful interventions are exercise and obesity reduction programs, as well as proper surveillance of patients with gastroesophageal reflux."

Vanier Canada Graduate Scholarship, Michael Smith Foreign Study Supplement, and Alberta Innovates Health Solutions partially supported this research. The authors declared no conflicts of interest.

SOURCE: http://bmj.co/1BRi5UR

Gut 2015