Colorectal cancer risk in relation to use of acid suppressive medications

Acid suppressants are commonly prescribed medications. Laboratory studies suggest a mechanism by which they could increase colorectal cancer (CRC) risk. A few epidemiologic studies have investigated acid suppressant use and CRC risk; none has documented an overall association. We sought to investigate whether acid suppressants are associated with CRC risk.

We conducted a case-control study among members of an integrated healthcare delivery system in Washington State. Cases (N = 641) were diagnosed with CRC between 2000 and 2003; controls (N = 641) were randomly selected from enrollees and matched to cases on age, sex, and length of enrollment. We used conditional logistic regression to estimate the odds ratios (ORs) and 95% confidence intervals (CI) for CRC associated with the use of any acid suppressive medication, proton pump inhibitors (PPIs) only, histamine receptor antagonists (H2 blockers) only, or both PPIs and H2 blockers in relation to the use of neither PPIs nor H2 blockers.

Use of PPIs exclusively was modestly associated with an increased risk of CRC, however this finding was consistent with chance and based on a small number of patients exposed (OR = 1.7; 95%CI = 0.8, 4.0). H2 blocker use alone was not related to CRC risk (OR = 0.8; 95%CI = 0.6, 1.1).

PPI use may be modestly associated with CRC risk; further research should be conducted in populations with long-term PPI use.