Bisphosphonate use might reduce risk of colorectal cancer

Internal Medicine World Report, Summer 2011, Volume 1, Issue 1

Bisphosphonate use might reduce risk of colorectal cancer

Class typically associated with success in treating breast cancer now shown to have positive impact in treating colorectal cancers

By Kurt Ullman

Bisphosphonate (BP) medications have recently been linked with a reduced risk for breast cancers. A study published recently in the Journal of Clinical Oncology explores the possibility that this class of medications may have a similar impact on colorectal cancers.

“When data appeared on the possible role of BPs in preventing development of metastases in women with breast cancer, I decided to look at their possible role for primary prevention in breast cancer,” said Gad Rennert, MD, from the Department of Community Medicine and Epidemiology at the Carmel Medical Center in Haifa, Israel. “When we found such an effect it was thought it might have been the background osteoporotic status reflecting a low estrogen exposure and not the drug itself. To resolve this question I decided to study the effect of the drug on a tumor site that is not influenced by circulating estrogen levels.”

The researchers looked at a subset of 933 pairs of postmenopausal women from northern Israel with colorectal cancer involved in the Molecular Epidemiology of Colorectal Cancer study. Long-term use of bisphosphonates were assessed in this group from pharmacy records. Cases and controls were matched by age, sex, clinic attended, and ethnic group and were drawn from the patient database of Clalit Health Services, the largest health care provider in the country. During the study years, it covered about 70% of those aged 60 years or older.

Use of BPs for more than a year prior to diagnosis, but not less than one year, was associated with significantly reduced relative risk (RR) of colorectal cancer (RR, 0.50; 95% confidence interval [CI], 0.35 to 0.71). The association remained significant after adjusting for vegetable consumption, sports activity, family colorectal cancer history, body mass index, and use of low-dose aspirin, statins, vitamin D, and postmenopausal hormone use (RR, 0.41; 95% CI, 0.25 to 0.67). Using BPs and statins together did not further reduce the risk.

“We found many more users of BPs among the healthy controls than among the colorectal cancer patients (all postmenopausal women),” said Dr. Rennert. “This translated into a preventive effect that after adjusting for many other known risk/protective factors for colorectal cancer was still very meaningful and significant. It is important to note that the BPs showed a preventive effect only after one year of use.”

Dr. Rennert stressed that there is still a need for validation from other studies, preferably randomized controlled trials.

“Once this happens we will be able to recommend such BPs treatment for cancer prevention given the relative high safety profile of this drug class,” he continued.

Author Disclosures: The authors noted no potential conflicts of interest.

Source: Rennert G, et al. Use of bisphosphonates and reduced risk of colorectal cancer. J Clin Oncol. 2011;

29:1146-1150.