Long-term effect of Helicobacter pylori eradication on colorectal cancer incidences

Abstract

<h3>Background:</h3><p>There is evidence supporting the association between <em>Helicobacter pylori</em> infection and colorectal cancer (CRC), but whether <em>H. pylori</em> eradication reduces the risk of CRC is still unknown.</p><h3>Objectives:</h3><p>To compare the incidence of CRC in subjects who had received <em>H. pylori</em> eradication therapy with general population.</p><h3>Design:</h3><p>A population-based retrospective cohort study.</p><h3>Methods:</h3><p>This study included all <em>H. pylori</em>-infected subjects who had received their first course of clarithromycin-containing triple therapy in 2003–2015 in Hong Kong. We compared the observed incidences of CRC in this <em>H. pylori</em> eradicated cohort with the expected incidences in the age- and sex-matched general population. The standardized incidence ratio (SIR) with 95% confidence interval (CI) was computed.</p><h3>Results:</h3><p>Among 96,572 <em>H. pylori</em>-eradicated subjects with a median follow-up of 9.7 years, 1417 (1.5%) developed CRC. Primary analysis showed no significant difference in the observed and expected incidences of CRC (SIR: 1.03, 95% CI: 0.97–1.09). However, when stratified according to the follow-up period, higher incidence of CRC was only observed in the first 5 years after eradication (SIR: 1.47, 95% CI: 1.39–1.55), but it was lower (SIR: 0.85, 95% CI: 0.74–0.99) than general population after 11 years. When stratified by tumor location, the observed incidence was higher for colon (SIR: 1.20, 95% CI: 1.12–1.29) but lower for rectal cancer (SIR: 0.90, 95% CI: 0.81–0.999) among <em>H. pylori</em>-eradicated subjects.</p><h3>Conclusions:</h3><p><em>H. pylori</em>-infected subjects appeared to have a higher incidence of CRC initially, which declined progressively to a level lower than general population 10 years after <em>H. pylori</em> eradication, particularly for rectal cancer.</p>