Women who have had
breast cancer may be at higher risk for
osteoporosis than other women. First, they are more likely to undergo early menopause, due to
chemotherapy-induced ovarian failure or oopherectomy. In addition,
chemotherapy may have a direct adverse effect on bone mineral density (BMD), and osteoclastic activity may increase from the
breast cancer itself. While
estrogen therapy is considered standard for the prevention and treatment of
osteoporosis, use of
estrogen in women with a history of
breast cancer is usually contraindicated. The approach to
osteoporosis in women with
breast cancer is also affected by the use of
tamoxifen in many, as this drug appears to have opposite effects on BMD in premenopausal and postmenopausal women. We have reviewed therapeutic alternatives for the prevention and treatment of
osteoporosis, focusing on patients with a history of
breast cancer.
Alendronate and
raloxifene are currently approved in the United States for the prevention of
osteoporosis;
alendronate,
raloxifene, and
calcitonin are approved for treatment.
Alendronate has the greatest positive effect on BMD and reduces the incidence of vertebral and nonvertebral fractures.
Raloxifene and
calcitonin appear to reduce the incidence of vertebral fractures; their effects on the incidence of nonvertebral fractures are not yet proven. Although no published studies specifically address the use of these approved agents for
osteoporosis in women with
breast cancer, understanding their relative effects on BMD in postmenopausal women in general will facilitate
therapy selection in this population. Postmenopausal women with a history of
breast cancer should undergo bone
mineral analysis. Normal results and absence of other risk factors ensure that
calcium and
vitamin D intake are adequate. If
osteopenia or other risk factors are present, preventive
therapy with
alendronate or
raloxifene should be considered. For
osteoporosis, treatment with
alendronate should be strongly considered.
Raloxifene and
calcitonin are alternatives when
alendronate is contraindicated. Further studies are needed to evaluate the optimal timing of initial bone
mineral analysis in premenopausal women after
breast cancer diagnosis and to determine the value of preventive treatment in women scheduled to undergo
chemotherapy.