Endoscopic screening was associated with an approximately 40% reduction in risk of death from gastric cancer in a systematic review and meta-analysis of studies from Asian countries.
The study is the first systematic review and meta-analysis of gastric cancer mortality and incidence after endoscopic screening, wrote Xing Zhang, MD, of the China Academy of Chinese Medical Sciences in Beijing with his associates. “Population-based prospective cohort studies are warranted to confirm our findings,” the reviewers wrote in the August issue of.
In general, the rates of gastric cancer and related mortality in East Asian countries are significantly higher than global averages. As a result, countries in this region have implemented a variety of national and opportunistic screening programs that vary from country to country. Japan, for example, has a national screening program based on photofluorography. “Although data are inconsistent, most studies have shown a 40%-60% decrease in the mortality of gastric cancer in those who have been screened using photofluorography,” the reviewers noted. When findings are positive, follow-up endoscopy is recommended. However, debates persist about whether population-level endoscopy significantly improves hard endpoints in gastric cancer, such as incidence and mortality.
To help clarify the population-level benefits of endoscopic screening, Dr. Zhang and his associates searched PubMed and EMBASE; they identified six cohort studies and four nested case-control studies that included approximately 342,000 adults from Asia who did not have baseline gastric cancer but did undergo surveillance endoscopy at least once. Studies of both mass and opportunistic screening were included. Each study included a comparator; reported incidence, mortality, or both; and was published by March 8, 2018.
Endoscopic screening was tied to a 40% reduction in the relative risk of death from gastric cancer (risk ratio, 0.60; 95% confidence interval, 0.49-0.73). There also was a slight trend toward increased incidence of gastric cancer, which was not statistically significant (RR, 1.14; 95% CI, 0.93-1.40). However, only two studies examined the incidence of gastric cancer, so this outcome “should be interpreted with caution,” the reviewers wrote. Endoscopic screening also was associated with a significantly lower risk of death from gastric cancer, compared with radiographic screening (RR, 0.33; 95% CI, 0.12-0.91).
Endoscopic screening did not significantly reduce mortality, compared with expected deaths (RR, 0.67; 95% CI, 0.38-1.16), the reviewers reported. This might be because the reviewers included an outlier study conducted in Linqu County, China, which has some of the highest rates of gastric cancer death in the world, they noted. Endoscopic surveillance did not reduce mortality in the Linqu County study, but screenings were spaced by 4.5 years, which was probably too long to show an effect, especially in a high-risk region, they added. The study in Linqu County accounted for most of the heterogeneity among studies, and removing it from the pooled analysis produced a “slightly more pronounced reduction in gastric cancer mortality,” with an RR of 0.56, they noted.
Funders included the National Natural Science Foundation and the National Twelfth Five-Year Plan for Science and Technology Support Program of China. The reviewers reported having no relevant conflicts of interest.
SOURCE: Zhang X, et al. Gastroenterology. 2018 Apr 30. .