Eliminating Helicobacter pylori May Significantly Decrease Gastric Cancer Risk

A study published in Gastroenterology suggested that successfully eliminating Helicobacter (H) pylori from a patient’s gastrointestinal tract could lead to a 75% reduction in risk of gastric carcinoma.¹

Researchers also found that racial and ethnic minorities, as well as smokers, were at significantly higher risk of gastric cancer after detection of H pylori.²

In this retrospective study of 371,813 veterans with a diagnosis of H pylori infection, the cumulative incidence of cancer at 5, 10, and 20 years after detection was 0.37%, 0.5%, and 0.65%, respectively. Patients who received treatment for their H pylori infection still had an increased risk of gastric cancer (sub-hazard ratio [SHR], 1.16; 95% CI, 0.74-1.83; P = 0.51), but patients who had confirmed H pylori eradication after treatment saw a reduced risk of gastric cancer (SHR, 0.24; 95% CI, 0.15-0.41; P < .001). 

“Re-testing [for H pylori] is a consensus guideline recommendation, but this happens very infrequently; less than 30% of patients were tested for eradication. But we demonstrated that it’s essential,” lead study author Shria Kumar, MD, gastroenterology fellow from Penn Medicine, said.

Factors associated with cancer included older age at time of detection of H pylori infection (SHR, 1.13; 95% CI, 1.11-1.15; P < .001), black/African American race (SHR, 2.00; 95% CI, 1.80-2.22), Asian race (SHR, 2.52; 95% CI, 1.64-3.89; P < .001 for race), Hispanic or Latino ethnicity (SHR, 1.59; 95% CI, 1.34-1.87; P < .001), or history of smoking (SHR, 1.38; 95% CI, 1.25-1.52; P < .001).

Women had decreased risk of gastric adenocarcinoma compared to men (SHR, 0.52; 95% CI, 0.40-0.68;  P<.001). Patients whose H pylori infection was detected based on serum antibody positivity also had a reduced risk of gastric cancer (SHR, 0.74; 95% CI, 0.54-1.04; P = 0.04).

“The problem was that all research out of the U.S. used to study gastric cancer and determine American’s risk of developing it did not take into account H pylori infection, and studies worldwide have shown this infection is actually the leading risk factor for this type of cancer,” Kumar said in a press release.

Though this retrospective epidemiology study was not equipped to indicate why tobacco users may be at higher risk, previous studies have established that smoking is a major risk factor for stomach cancer. However, this study further emphasizes the need to stress smoking cessation to patients. 

More than half of the world’s population is infected with H pylori, according to a 2017 article published in Gastroenterology. The prevalence of the infection varies globally according to socioeconomic factors and levels of hygiene; however, the global prevalence was estimated to be 4.4 billion people infected in 2015.³

According to Kumar, H pylori is the most important risk factor for gastric cancer and has been labeled as a class 1 carcinogen. Of those that had the infection, at 20 years the cumulative incidence was 0.65% (about 1/150). However, the vast majority of people with it have no symptoms at all and never develop stomach cancer. 

References:

1. Eliminating Common Bacterial Infection Significantly Decreases Gastric Cancer Risk [news release]. Philadelphia, Pennsylvania. Published November 14, 2019. pennmedicine.org/news/news-releases/2019/november/eliminating-common-bacterial-infection-significantly-decreases-gastric-cancer-risk. Accessed December 5, 2019.

2. Kumar S, Metz DC, Ellenberg S, Kaplan DE, Goldberg DS. Risk Factors and Incidence of Gastric Cancer After Detection of Helicobacter pylori Infection: A Large Cohort Study. Gastroenterology. doi:10.1053/j.gastro.2019.10.019.

3. Hooi JKY, et al. Global prevalence of Helicobacter pylori infection: Systematic review and meta-analysis. Gastroenterology. doi:10.1053/j.gastro.2017.04.022.