Current use of tamoxifen is associated with a marked reduction in osteoporotic fractures, according to a study published online by the Journal of Clinical Oncology.

Current use of tamoxifen is associated with a marked reduction in osteoporotic fractures, according to a study published online by the Journal of Clinical Oncology.

"Although tamoxifen has been shown to increase bone mineral density in clinical trials, it is less clear whether this significantly affects fracture rates," Dr. Andrew L. Cooke, of CancerCare Manitoba, Winnipeg, Canada, and colleagues write. "Even fewer data are available on skeletal outcomes when tamoxifen is used outside of the context of a clinical trial."

The researchers conducted a population-based, case-control study to examine whether tamoxifen use is associated with osteoporotic fractures in routine clinical practice.

Using data from the Manitoba Department of Health, the team identified 11,096 women at least 50 years of age with fractures, and compared each with three controls without fracture, matched for age, ethnicity, and comorbidity (n = 32,209). Tamoxifen use was categorized as never used, remote past use, recent past use, and current use.

Overall, 324 patients (2.9 per cent) and 1123 controls (3.4 per cent) had a breast cancer diagnosis. Approximately 72 per cent of breast cancer patients reported using tamoxifen at some time. Current tamoxifen use was identified in 105 cases (0.9 per cent) and 459 controls (1.4 per cent).

Current tamoxifen use was associated with lower osteoporotic fracture rates (univariate OR = 0.68). Remote or recent past tamoxifen use was not related to osteoporotic fractures.

"Women with hip fracture were significantly less likely to be current tamoxifen users (adjusted OR = 0.47)," Dr. Cooke's team reports. "ORs for wrist fractures alone (0.84) and spine fractures alone (0.73) showed a similar trend but were not statistically significant."

The authors note that breast cancer was not independently associated with osteoporotic fractures (adjusted OR = 0.95).

J Clin Oncol 2008;26