From the AGA Journals

Endoscopic screening tied to significantly lower risk of death from gastric cancer

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Surveillance identifies more cancers earlier

Gastric cancer remains the third most common cause of cancer death worldwide, although incidence and mortality rates have been declining for several years. For populations in eastern Asia – a region that carries the unenviable tag of having the highest gastric cancer mortality rates in the world – finding ways to reduce the burden of this disease remains a key priority.
New findings reported by Zhang and his colleagues have highlighted a strong evidence base for one mode of gastric cancer control in eastern Asia. The systematic review team demonstrated a significant 40% reduction in the risk of death from gastric cancer when screening was conducted in general populations. The magnitude of this benefit likely reflects the appropriateness of screening in such high-incidence areas, although this finding might not necessarily be extrapolated to other regions.

The authors cautioned that screening did not reduce gastric cancer incidence, although only two studies were included. However, reduced incidence is often not an aim of screening programs; indeed, to detect more gastric cancers at an earlier stage can be an intentional outcome.

The observed benefits might be somewhat attributed to lead time bias (whereby individuals are diagnosed at a younger age than they would have presented symptomatically but still die at the same age) or length time bias (detecting only the slower-growing biological tumors). Further refinement of optimal screening intervals is also required. Nevertheless, public health policy makers in Japan and Korea, where national screening programs already exist, should be reassured by these review findings.

Helen Coleman, PhD, BSc(Hons), is a senior lecturer and lead of the Cancer Epidemiology Research Group at the Centre for Public Health and Centre for Cancer Research and Cell Biology at Queen’s University Belfast. She has no conflicts of interest.



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 Gastroenterology.

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. doi: 10.1053/j.gastro.2018.04.026.

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