Postdiagnosis and Pre-/Postdiagnosis Use of Bisphosphonates for Osteoporosis Reduces Risk of Skeletal Metastases in Women With Breast Cancer
In a Canadian study reported in the Journal of the National Cancer Institute, Kremer et al found that postdiagnosis use only or pre-and postdiagnosis use of bisphosphonates for treatment or prevention of osteoporosis in postmenopausal women with breast cancer was associated with a significant reduction in risk of skeletal metastases.
Study Details
The study involved health administrative data from a historical cohort of 21,664 women diagnosed with breast cancer in Quebec, Canada, including 16,669 with local (stage 0–II) and 4,850 with regional (stage III) disease. Bisphosphonates were used by 30% of patients with local disease, including prediagnosis only in 1%, postdiagnosis only in 19%, and pre- and postdiagnosis in 10%. Bisphosphonates were used by 21% of patients with regional disease, including prediagnosis only in 2%, postdiagnosis only in 12%, and pre- and postdiagnosis in 6%.
Risk of Skeletal Metastases
Compared with no bisphosphonate use among patients with local disease, risk of bone metastases was significantly increased (hazard ratio [HR] = 2.03, 95% confidence interval [CI] = 1.26–3.26) in patients with prediagnosis bisphosphonate use only and significantly reduced in those with postdiagnosis use only (HR = 0.55, 95% CI = 0.44–0.69) and in those with pre- and postdiagnosis use (HR = 0.72, 95% CI = 0.53–0.98). Among patients with regional disease, risk vs no bisphosphonate use was not significantly different in those with prediagnosis use only (HR = 1.21, 95% CI = 0.60–2.11) and was significantly reduced in those with postdiagnosis use only (HR = 0.51, 95% CI = 0.40–0.65) and in those with pre- and postdiagnosis use (HR = 0.50, 95% CI =0.33–0.75).
Mortality
Compared with no bisphosphonate use, patients with local disease had significantly increased risk of overall mortality (HR = 1.37) and cancer-related mortality (HR = 1.78) with prediagnosis use only and reduced risk of overall mortality and cancer-related mortality with postdiagnosis use only (HRs = 0.48 for both) and pre- and postdiagnosis use (HRs = 0.70 and 0.66). Patients with regional disease had significantly increased risk of overall mortality with prediagnosis use only (HR = 1.44) and significantly reduced risk of overall and cancer-related mortality with postdiagnosis use only (HRs = 0.43 and 0.44) and significantly reduced risk of overall mortality with pre- and postdiagnosis use (HR = 0.76).
The investigators concluded: “Low-dose oral bisphosphonates administered for prevention or treatment of postmenopausal osteoporosis were associated with lower risk of skeletal metastasis in patients with early- or more advanced-stage breast cancer.”
Richard Kremer, MD, of McGill University Health Centre, is the corresponding author for the Journal of the National Cancer Institute article.
The study was supported by the Canadian Institutes of Health Research, Susan G. Komen Foundation, Canadian Breast Cancer Research Initiative, McGill University Health Centre Research Institute, and Quebec Network for Research on Drug Use. The study authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
