Exposure to bisphosphonates and risk of colorectal cancer

Abstract

Chemoprevention is a potentially attractive strategy for decreasing the burden of colorectal cancer (CRC). Preclinical studies suggest that bisphosphonates (BPs) may have direct antitumour effects against CRC. The objective of this study was to determine the effect of exposure to BPs on the incidence of CRC. The Manitoba Cancer Registry was used to identify patients who were diagnosed with CRC from 2000 to 2009 who had been living in Manitoba for at least 5 years before diagnosis (cases). Each case was matched to 10 controls of similar age, sex, and duration of residence in Manitoba using incidence density sampling. Exposure to BPs was determined using the provincial Drug Program Information Network database. Conditional logistic regression analysis was performed to determine the effect of exposure to BPs on CRC incidence with adjustment for health care use, medical procedures (including lower gastrointestinal endoscopy), socioeconomic status, and pre-existing health conditions. In total, 5425 patients with CRC were matched to 54,242 controls. In the multivariate analysis, exposure to BPs was associated with a reduction in the risk of CRC (2-13 BP prescriptions over ≥5 years: odds ratio [OR] 0.84; 95% confidence interval [CI], 0.71-1.00; ≥14 BP prescriptions over ≥5 years: OR, 0.78; 95% CI, 0.65-0.94). When the effect of specific BP agents was evaluated, the effect was significant only for exposure to risedronic acid (OR, 0.50; 95% CI, 0.30-0.85). There was no significant effect of increasing duration or cumulative dose of alendronic acid. The results from this study suggested that exposure to BPs, especially risedronic acid, may be associated with a decreased risk of developing CRC.