Although H. pylori infection does not itself cause illness but, chronic infection is associated with long-lasting inflammation in the stomach, which can cause complications like atrophic gastritis and stomach cancer.
According to a study published in the Journal of Clinical Oncology, H. pylori-positive individuals may exhibit a small yet statistically significant increase in the incidence and mortality rates of colorectal cancer (CRC). Untreated individuals, especially those with active infections, seem at the most significant risk.

Helicobacter pylori is the most common cause of infection-associated cancer worldwide. This study evaluated the impact of H. pylori infection and treatment on CRC incidence and mortality.
The study included patients in the US who completed H. pylori testing between 1999 and 2018. They conducted a retrospective cohort analysis among adults within the Veterans Health Administration who completed testing for H. pylori. The primary exposures were H. pylori test results (positive/negative) and treatment (untreated/treated) among H. pylori-positive individuals. The primary outcomes were CRC incidence and mortality. Follow-up started at the first H. pylori testing and continued until the earliest incident or fatal CRC, non-CRC death, or December 31, 2019.
Key findings of the study are:
25.2 % of individuals among 812,736 tested positive for H. pylori.
Being H. pylori–positive versus H. pylori–negative was associated with higher CRC incidence and mortality.
H. pylori treatment versus no treatment was associated with lower CRC incidence and mortality through 15-year follow-up.
Being H. pylori–positive versus H. pylori–negative was associated with an 18 % and 12% higher incident and fatal CRC risk, respectively. The aHR was 1.18 and 1.12, respectively.
Individuals with untreated versus treated H. pylori infection had 23% and 40% higher incident and fatal CRC risk, respectively, with aHR of 1.23 and 1.40.
The results were more pronounced in the analysis restricted to individuals with nonserologic testing.
Concluding further, they said that H. pylori infection is linked to a higher incidence and mortality rate for colorectal cancer (CRC), particularly in those with active infections and who are untreated. The association is small but significant, they added.
Reference:
Shailja C. Shah et al. Impact of Helicobacter pylori Infection and Treatment on Colorectal Cancer in a Large, Nationwide Cohort. JCO 0, JCO.23.00703
DOI:10.1200/JCO.23.00703