Bisphosphonates (like Fosamax) and Various Cancers

Bisphosphonate drugs like Fosamax® protect against osteoporosis and its associated fractures.  It’s less well known that they can protect against the risk of 3 serious cancers – breast, colon, and uterus (endometrium). 

An important study on the association between use of bisphosphonates and the risk of postmenopausal breast cancer was published in 2009 in the Journal of Clinical Oncology. Israeli researchers showed, in a study of 4,000+ patients that the use of bisphosphonates for more than one year was associated with a significantly reduced risk (28%) of breast cancer.  Moreover, tumors that did develop under bisphosphonates treatment tended to have a favorable prognostic factors profile.  This year, a presentation at the San Antonio Breast Cancer Symposium confirmed that women taking osteoporosis drugs had a 30% lower risk of breast cancer than women not taking them. 

Also in 2011, Canadian researchers reported in the journal Cancer that exposure to bisphosphonates may be associated with a decreased risk of developing colorectal cancer.  And in a presentation at the 2011 Gastrointestinal Cancers Symposium, Israeli scientists examined data from 933 postmenopausal women who developed colorectal cancer and 933 matched female controls between 1998 and 2004.  Use of bisphosphonates for more than a year was associated with a 50% reduction in the risk of colorectal cancer.

Finally, the European Society of Gynecological Oncology had a presentation of results from the Cancer of the Uterus and Ovary Study, coming from Carmel Medical Center, California. Researchers matched 212 consecutive patients with endometrial cancer with 199 women without cancer.  Bisphosphonate use was available from prescription records for all the subjects.  There were 9& of the cancer patients who had used bisphosphonates, compared with 24% of the controls.  This translated into a 61% reduction in the risk of endometrial cancer among bisphosphonate users.

The apparent beneficial association of bisphosphonates’ use with a lowered risk of a number of cancers has to be set against their relationship with esophageal cancer.  This risk is, however, quite small: roughly 2 cancer cases in 1,000 patients after 5 years’ therapy, compared with I in 1,000 matched subjects not taking the drugs.  Although a doubling of the risk, this is small enough to allow us to say that the benefits of these drugs outweighs their risk.