Helicobacter Pylori Linked to Increased Colorectal Cancer Risk, Study Finds

• Despite ongoing debate, increasing evidence suggests Helicobacter pylori may contribute to colorectal cancer (CRC).
• Analysis of 43 studies indicates H. pylori exposure correlates with a 1.59-fold rise in CRC risk.
• Limited studies show eradication of the bacterium reduces CRC incidence after prolonged observation periods.

New research highlights a potential link between Helicobacter pylori infection and colorectal cancer (CRC), expanding beyond its well-documented role in gastric malignancies. A risk-attribution modeling study led by Shailja C. Shah, MD, MPH, at the University of California San Diego, analyzed data from 43 studies to quantify this relationship.

The study, published in eGastroenterology, found individuals with H. pylori exposure faced a 1.59-fold increased risk of CRC (95% CI 1.36-1.87). Globally, approximately 22% of CRC cases (95% UI 14.7-29.4) could theoretically be attributed to H. pylori infection. However, this figure dropped to 11.9% (95% UI 0.7-22.8) when restricting analysis to 14 population-based and cohort studies.

Observational studies of H. pylori eradication suggest a delayed protective effect against CRC, with risk reduction observed only after a decade or more of follow-up. The authors emphasize that these findings are exploratory and require validation through rigorous, prospective trials to establish causation.

“While preliminary, these results align with successes in population-level H. pylori eradication campaigns for gastric cancer prevention and may warrant expanded focus in high-prevalence, resource-limited regions,” the researchers note. They further suggest such strategies could yield dual benefits for CRC risk reduction.

The International Agency for Research on Cancer (IARC) classifies H. pylori as a Group 1 carcinogen due to its proven role in gastric cancer. Its involvement in CRC remains contentious, though a 2019 U.S. veteran cohort study reported an 18% heightened CRC likelihood among infected individuals. The current analysis, however, calls for stronger evidence to confirm an exposure-response relationship.

The study authors advocate for targeted public health strategies and research to address CRC prevention beyond gastric cancer goals. They utilized global cancer incidence data from the International Cancer Observatory, examining variations by sex, age, geography, and birth cohorts.

Regional disparities emerged: women exhibited higher potential attributable fractions (24.8% vs. 19.9% in men), and more recent birth cohorts showed elevated estimates (15% among those born 1963-1977). Japan, Portugal, and South Korea led in age-standardized CRC rates linked to H. pylori (9.0, 8.4, and 7.8 per 100,000, respectively), while the U.S. recorded 2.5 per 100,000. Western Pacific nations and Mongolia bore the highest global proportions (25-36%), though Africa and parts of Asia maintained high prevalence with lower CRC attribution.

“Evidence directly testing eradication’s CRC impact is sparse and limited by short study durations and confounding variables,” the team cautions. “Robust prospective and interventional studies are essential to clarify H. pylori‘s role in CRC and inform preventive interventions.”

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