Long-term effect of eradication on colorectal cancer incidences.

BACKGROUND

There is evidence supporting the association between infection and colorectal cancer (CRC), but whether eradication reduces the risk of CRC is still unknown.

OBJECTIVES

To compare the incidence of CRC in subjects who had received eradication therapy with general population.

DESIGN

A population-based retrospective cohort study.

METHODS

This study included all -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 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.

RESULTS

Among 96,572 -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 -eradicated subjects.

CONCLUSIONS

-infected subjects appeared to have a higher incidence of CRC initially, which declined progressively to a level lower than general population 10 years after eradication, particularly for rectal cancer.