(ChemotherapyAdvisor) – A large prospective cohort study has found no association between long-term use of bisphosphonates and risk of colon cancer, investigators reported in the Journal of Clinical Oncology online May 29.

Although an inverse association between bisphosphonate use and colorectal cancer has been suggested, data from prospective cohorts are lacking, Andrew T. Chan, MD, MPH, of Massachusetts General Hospital, Boston, MA, and colleagues reported. In this study, the relationship between bisphosphonate use and risk of colorectal cancer was examined among 86,277 women enrolled in the Nurses Health Study. “Since 1998, participants have returned biennial questionnaires in which they were specifically queried about the regular use of bisphosphonates,” Dr. Chan wrote.

A total of 801 cases of colorectal cancer over 814,406 person-years of follow-up were documented through 2008. Age-adjusted HR for women who regularly used bisphosphonates was 0.92, which was further attenuated after adjustment for other risk factors (multivariate HR, 1.04).

Continue Reading

Risk was not influenced by duration of use (Ptrend=0.79). Compared with nonusers, multivariate-adjusted hazard ratios of colorectal cancer were 1.24 for women with 1 to 2 years of use, 1.16 for 3 to 4 years of use, and 0.97 for ≥5 years of use. No association was observed between bisphosphonate use and colorectal cancer within strata of other risk factors.

“In summary, although bisphosphonates are recommended for many individuals with osteoporosis and skeletal metastases, in this prospective cohort study, we found no support for the hypothesis that bisphosphonates prevent colorectal cancer,” Dr. Chan noted. “As with statin drugs, additional prospective studies may not confirm the promising results of case-control studies.”