Eradication of Helicobacter pylori infection was associated with a more than 75% decrease in hazard of subsequent stomach cancer in a large retrospective cohort study.
Simply being treated for H. pylori infection did not mitigate the risk of gastric adenocarcinoma, and patients whose H. pylori was not eradicated were at increased risk, said Shria Kumar, MD, of the Perelman Center for Advanced Medicine in Philadelphia, and with her associates. “This speaks to the ability of H. pylori eradication to modify future risks of gastric adenocarcinoma, and the need to not only treat those diagnosed with H. pylori, but to confirm eradication, and re-treat those who fail eradication,” they wrote in Gastroenterology.
Gastric adenocarcinoma remains a grave diagnosis, with a 5-year survival rate of less than 30%. Although H. pylori infection is an established risk factor for gastric cancer (particularly nonproximal disease), most studies have used national cancer databases that do not track H. pylori infection. Accordingly, Dr. Kumar and her associates analyzed data for 371,813 patients diagnosed with H. pylori infection at U.S. Veterans Health Administration facilities between 1994 and 2018. A total of 92% of patients were men, 58% were white, 24% were black, and approximately 1% each were Native American, Asian, or Native Hawaiian/Pacific Islander. Median age was 62 years.
Patients with H. pylori infection who subsequently were diagnosed with nonproximal gastric cancer were significantly (P less than .001) more likely to be older (median age, 65.1 vs. 62.0 years), current or historical smokers, or racial or ethnic minorities (black or African American, Asian, or Hispanic/Latino), compared with patients with H. pylori who did not develop cancer. In the multivariable analysis, standardized hazard ratios for these variables remained statistically significant, with point estimates ranging from 1.13 (for each 5-year increase in age at diagnosis of infection) to 2.00 (for black or African American race). Cumulative incidence rates of distal gastric adenocarcinoma following H. pylori infection were 0.37% at 5 years, 0.5% at 10 years, and 0.65% at 20 year.
Patients whose infections were confirmed to have been eradicated were at markedly lower risk for subsequent gastric cancer than were patients whose infections were not eradicated (SHR, 0.24; 95% confidence interval, 0.15-0.41; P less than .001). Importantly, simply being treated for H. pylori did not significantly affect cancer risk (SHR, 1.16; 95% CI, 0.74-1.83).
Rates in Japan are approximately five times higher, while in sub-Saharan Africa, H. pylori infection is prevalent but gastric cancer is uncommon, the researchers noted. These discrepancies support the idea that carcinogenesis depends on additional genetic or environmental variables in addition to H. pylori infection alone, they said. They called for future studies of protective factors.
Dr. Kumar is supported by a training grant from the National Institutes of Health. She disclosed travel support from Boston Scientific and Olympus. Her coinvestigators disclosed ties to Takeda, Novartis, Janssen, Gilead, Bayer, and several other companies.
SOURCE: Kumar S et al. Gastroenterology. 2019 Jul 31. doi: 10.1053/j.gastro.2019.10.019.