H. Pylori Testing Did Not Reduce Gastric Cancer Incidence, Mortality

An invitation to undergo screening for Helicobacter pylori stool antigen did not reduce rates of gastric cancer incidence or mortality, according to results from a Taiwanese randomized trial.

Among participants who underwent H. pylori testing along with a fecal immunochemical test (FIT) for colorectal cancer screening, the gastric cancer incidence rate was 0.032% compared with 0.037% for those who only completed FIT (P=0.23), and gastric cancer mortality rates were 0.015% and 0.013%, respectively (P=0.57), reported Tony Hsiu-Hsi Chen, PhD, of National Taiwan University, and colleagues.

However, in post hoc analyses, after adjusting for differences in screening participation, length of follow-up, and patient characteristics, incidence of gastric cancer was statistically significantly lower in the group who underwent H. pylori testing plus FIT compared with FIT alone (relative risk [RR] 0.79, 95% CI 0.63-0.98, P=0.04), but this was not the case for gastric cancer mortality (RR 1.02, 95% CI 0.73-1.40, P=0.91), they wrote in JAMA.

H. pylori is a contributing factor to the development of gastric cancer, and bacterial eradication treatment may prevent its occurrence, the authors noted.

“However, whether community screening for H. pylori can reduce rates of gastric cancer or gastric cancer mortality remains unknown,” they wrote. Thus, this community-based randomized trial was designed to test whether inviting participants to undergo H. pylori testing and treatment along with FIT would reduce gastric cancer incidence and mortality.

In an editorial accompanying the study, M. Constanza Camargo, PhD, MSc, of the National Cancer Institute, noted that in a fully adjusted as-treated analysis, adding an H. pylori test significantly reduced both gastric cancer incidence (RR 0.58, 95% CI 0.42-0.78) and mortality (RR 0.50, 95% CI 0.32-0.78).

However, she pointed out that there were “stark differences” in intervention adherence that made this as-treated analysis likely biased.

For example, she said that the participation rate was higher in the H. pylori/FIT group, and that there was differential follow-up time between the groups. Participants in the H. pylori/FIT group also had a greater number of risk factors for gastric cancer compared with the FIT-only group.

“Despite these limitations, this innovative trial conveys valuable insights for the primary prevention of gastric cancer, with potential application to diverse settings,” Camargo wrote. “Notably, the results show that implementation of H. pylori test-and-treat strategies is indeed possible using screening platforms already in place.”

For this study conducted from January 2014 through September 2018, Chen and colleagues randomized adults ages 50 to 69 (mean age 58, 46.8% women) in Changhua County, Taiwan to an invitation to undergo H. pylori testing plus FIT or FIT alone. Screening participation rates were 49.6% for the H. pylori/FIT group (n=31,497) and 35.7% for the FIT-alone group (n=31,777).

Of the participants tested for H. pylori, 38.5% had a positive result. Of these patients, 72.5% were referred for treatment and 98.4% completed treatment. After one or two courses of antibiotic treatment, H. pylori eradication rates were 91.9% and 97.6% for patients who took medication and for those who used at least 80% of the medication, respectively.

FIT positivity rates were similar (about 7%) for both groups.

Among participants who received antibiotics, the most common adverse effects were abdominal pain or diarrhea (2.1%) and dyspepsia or poor appetite (0.8%).

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