Osteoporosis drugs may benefit breast cancer patients too

Women taking oral bisphosphonates are about one-third less likely to develop invasive breast cancers than women not taking such drugs, the study results presented Thursday at the San Antonio Breast Cancer Symposium revealed.

The first study
The first study analyzed data from the Women’s Health Initiative (WHI), a federally funded study led by Dr. Rowan Chlebowski of Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center in Torrance, California.

Nearly 150,000 postmenopausal women who participated in the WHI study were assessed. 2,216 were taking bisphosphonates, mostly Fosamax, at the start of the study.

Upon seven-year follow-up, women taking bisphosphonates were 32 percent less likely to report invasive breast cancer compared to women not taking such drugs, researchers revealed.

The results were tabulated after taking into account differences in age, smoking, weight, hormone and vitamin D use, all of which affect bone density and breast cancer risk in women.

The second study
In the second study, researchers at the Technion-Israel Institute of Technology in Haifa, Israel, followed about 4,000 postmenopausal women. While 2,000 postmenopausal women were diagnosed with breast cancer, others were not.

Women who had used bisphosphonates for a year or more saw a 29 percent reduction in invasive breast cancer tumors than women who were not prescribed such drugs, researchers revealed.

Upshot of the findings
Bisphosphonates, a class of drugs are that help prevent loss of bone mass, are also potent in combating bone loss associated with hormonal therapy. Moreover, such drugs also help in treating complications that result from breast cancer spreading to the bones, as they inhibit the spread.

"Bone loss and potential fractures are a known complication of breast cancer therapy. Our feeling is that bisphosphonates may actually prevent disease recurrence through a variety of mechanisms," Dr. Adam Brufsky, associate director of clinical investigation at the University of Pittsburgh Cancer Institute, marked.

Researchers emphasize caution in interpreting the new studies
Though the findings of the two observational studies seem exciting, experts underline reason for caution in interpreting the new studies.

As taking oral bisphosphonates is generally synonymous to treating low bone mineral density especially occurring in old age, prescribing the drug for combating breast cancer can be impractical.

Breast cancer usually triggers in late-middle age, and the risk increases with higher lifelong exposure to estrogen. Conversely, osteoporosis risk stems from lower estrogen levels, researchers note.