Oral bisphosphonates and colorectal cancer

Use of oral bisphosphonates has been associated with a decreased risk of colorectal cancer (CRC), but the association may be related to residual confounding by healthy lifestyle or body mass index (BMI). Therefore, we conducted a prospective nested case-control study within the Kaiser Permanente, Northern California health system cohort. In total, 12,505 CRC cases were individually matched to 599,534 controls. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using conditional logistic regression models with adjustment for important covariates extracted from the database. Participants who had ever used oral bisphosphonates were less likely than non-users to be diagnosed with CRC (OR 0.82; 95% CI: 0.74, 0.89). Colon and rectum site-specific associations were similar to the overall association. A stronger inverse association for ever use of bisphosphonates was observed for men (OR 0.63; 95% CI: 0.47, 0.85), however when stratified by previous lower endoscopy, the association was only observed in the participants who did not have a previous lower endoscopy (OR 0.73 (0.64, 0.83)). In conclusion, we found that oral bisphosphonate use was associated with a decreased odds of CRC, however this association may be due to residual confounding by BMI or another confounder.