Following Helicobacter pylori Infection, Gastric Cancer Risk High

Helicobacter pylori, bacterium which causes gastric and duodenal ulcer
Individuals who are racial or ethnic minorities and individuals who are smokers experience significantly higher risks for gastric cancer following a diagnosis of Helicobacter pylori infection.

Individuals who are racial or ethnic minorities and individuals who are smokers experience significantly higher risks for gastric cancer following a diagnosis of Helicobacter pylori (H pylori) infection, according to research published in Gastroenterology.

H pylori infection is the most well-known risk factor for gastric cancer. Investigators conducted a retrospective cohort study aimed at identifying the incidence of non-proximal gastric adenocarcinoma following H pylori infection. Additional aims included defining how demographics, environmental factors, and infection treatment modality affect the incidence of gastric cancer.

In total, 371,813 patients with H pylori were identified: 26,873 via endoscopic pathology, 11,262 via stool antigen, 400 via urea breath test, 266,216 via prescription of an eradication regimen, and 67,062 with administrative codes. Within the overall cohort, 0.54% of patients developed gastric adenocarcinoma over a median follow-up of 7.4 years. These patients were most likely to be older black men and to have a history of smoking. Median age at cancer diagnosis was 69 years. Moreover, the patients who developed cancer were more likely to have died (67.7% vs 37.2%).

Among patients with a positive diagnostic test, 74.8% were prescribed an eradication regimen; 20.8% then underwent retesting. Among those, the infection was successfully eradicated in 90.9%.

Multivariable competing-risk models identified several factors associated with incident diagnosis, including the H pylori diagnosis method. Patients diagnosed based only on the International Classification of Diseases code with a positive serum antibody in the adjacent 90 days were at the lowest risk (sub-hazard ratio [SHR] 0.75; 95% CI, 0.62-0.90). Additional factors associated with future gastric adenocarcinoma included each 5-year increase in age at H pylori diagnosis (SHR 1.13; 95% CI, 1.11-1.15), being black (SHR 2.00; 95% CI, 1.80-2.22), and Asian race or Hispanic ethnicity (SHR 2.52 [95% CI, 1.64-3.89] and 1.59 [95% CI, 1.34-1.87]), respectively). Smoking history was also associated with future gastric adenocarcinoma (SHR 1.38; 95% CI, 1.25-1.52).

Within this same sub-population, H pylori treatment was not associated with subsequent development of gastric adenocarcinoma (SHR 1.16; 95% CI, 0.74-1.83). Patients with confirmed H pylori who underwent eradication testing experienced a significantly lower risk for gastric adenocarcinoma (SHR 0.24; 95% CI, 0.15-0.41), although age, race, ethnicity, and tobacco history were all still associated with cancer development.

Finally, sensitivity analyses demonstrated that gastric adenocarcinoma incidence following H pylori diagnosis at 5, 10, and 20 years was 0.19%, 0.33%, and 0.49%, respectively, excluding cancers that developed within 6 months of treatment. After excluding cancers that developed within 12 months, these incidences were 0.24%, 0.38%, and 0.53%, respectively.

Study limitations included the retrospective nature of the research, inherent selection bias, a lack of generalizability due to use of a cohort made up of >90% men, and the inability to identify potential confounders.

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“Future studies should focus on consideration of screening of high-risk persons, identification of what host and [H pylori] factors predispose to increased risk, quality measures to ensure appropriate diagnosis of [H pylori] infection, and resistance patterns and efficacy treatment of [H pylori] infection,” the researchers concluded.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

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 [published online October 22, 2019]. Gastroenterology. doi: 10.1053/j.gastro.2019.10.019