NCI Cancer Bulletin for February 22, 2011 - National Cancer Institute: Bisphosphonate Use May Reduce Colorectal Cancer Risk

Bisphosphonate Use May Reduce Colorectal Cancer Risk

Post menopausal women who used bisphosphonate drugs (primarily alendronate) for more than 1 year had a 59 percent lower risk of colorectal cancer, according to a study published online February 14 in the Journal of Clinical Oncology. The findings came from a population-based, case-control study of colorectal cancer in northern Israel.

Bisphosphonates are commonly prescribed to treat or prevent osteoporosis and are also used to treat bone metastases in patients with breast cancer. Laboratory studies have shown that these drugs can interfere with steps involved in cancer cell growth and spread, and thus may have anticancer properties in humans. Indeed, previous reports have shown fewer breast cancer cases in women taking bisphosphonates. However, these studies did not rule out whether the reduced breast cancer risk was due to the lower estrogen levels often found in women who have low bone density and who are thus more likely to use bisphosphonates. (Colorectal cancer is not known to be fueled by estrogen.)

Analyzing data from the Molecular Epidemiology of Colorectal Cancer study, Dr. Gad Rennert of Technion-Israel Institute of Technology in Haifa, Israel, and his colleagues compared 933 women diagnosed with colorectal cancer with 933 women who did not have the disease. The women in the two groups were matched by age, ethnicity, and area of residence. The researchers also adjusted for known colon cancer risk factors, including vegetable consumption, sports activity, family history of colorectal cancer, body mass index, and use of low-dose aspirin, statin drugs, vitamin D, and postmenopausal hormones.

“This evidence does not provide a basis for using bisphosphonates for colorectal cancer prevention,” cautioned Dr. Asad Umar of NCI’s Division of Cancer Prevention. “Indications for these drugs may be limited due to their toxic side effects, including rare cases of osteonecrosis of the jaw, esophagitis and esophageal erosion, and a possible higher risk of bone fractures after prolonged use.” A controlled clinical trial would be needed to confirm the connection between bisphosphonate use and colorectal cancer risk, he concluded.

NCI Cancer Bulletin for February 22, 2011 - National Cancer Institute