Bisphosphonates reduce colorectal cancer risk

Postmenopausal women who have taken an oral bisphosphonate longer than 1 year have a 59% reduced risk for colorectal cancer, according to the findings of the Molecular Epidemiology of Colorectal Cancer study. The population-based, case-control study comes from the same Israeli group that reported last year that bisphosphonate use was associated with a reduced risk for breast cancer.

Using computerized pharmacy records, the researchers identified almost 2,000 women (933 postmenopausal women with colorectal cancer, 53 of whom had used a bisphosphonate longer than 1 year, and 933 control subjects, matched for age, religion, and residence, 100 of whom had used a bisphosphonate longer than 1 year).

They found that use of a bisphosphonate longer than 1 year before a diagnosis of colorectal cancer, but not less than 1 year, reduced the risk for colorectal cancer by half (relative risk [RR], 0.50; 95% confidence interval [CI], 0.35-0.71). After adjusting for vegetable consumption, sports activity, family history of colorectal cancer, body mass index, and use of low-dose aspirin, statins, vitamin D, and postmenopausal hormones, the reduced risk remained statistically significant (RR, 0.41; 95% CI, 0.25-0.67). Concomitant use of bisphosphonates and statins did not yield further reduction.

Oral bisphosphonates are believed to exert a cancer-protective effect in a manner similar to that of statins because they share a common metabolic pathway. The study authors say a randomized trial is needed to confirm the findings.

Rennert G, Pinchev M, Rennert HS, Gruber SB. Use of bisphosphonates and reduced risk of colorectal cancer. J Clin Oncol. February 14, 2011. [Epub ahead of print.]