Bisphosphonates for osteoporosis treatment are associated with reduced breast cancer risk

Abstract

Background: Bisphosphanates are used primarily for the prevention and treatment of osteoporosis, and are also indicated for osseous complications of malignancy. In addition to their bone resorption properties, the most commonly used nitrogen-containing bisphosphonate compounds also inhibit protein prenylation, and thus may exert anti-tumour properties.

Methods: To evaluate whether the use of these drugs may be associated with cancer, specifically breast cancer, we conducted a population-based case-control study in Wisconsin from 2003 to 2006. Participants included 2936 incident invasive breast cancer cases and 2975 population controls aged < 70 years. Bisphosphonate use and potential confounders were assessed by interview.

Results: Using multivariable logistic regression, the odds ratio for breast cancer in current bisphosphonate users compared with non-users was 0.67 (95% confidence interval 0.51-0.89). Increasing duration of use was associated with a greater reduction in risk (P-trend=0.01). Risk reduction was observed in women who were not obese (P-interaction=0.005).

Conclusion: These results are suggestive of an additional benefit of the common use of bisphosphonates, in this instance, the reduction in breast cancer risk.

Figure 1

Odds ratios and 95% confidence intervals of breast cancer according to bisphosphonate use and body mass index (BMI). Odds ratios were adjusted for age at diagnosis, party, age at first live birth, family history of breast cancer, BMI menopausal status, age at menopause, type of hormone use, mammography, osteoporosis, smoking history, and height change. P-interaction for BMI and use of bisphosphonates=0.005.