Most women with early
breast cancer (BC) have an excellent prognosis and will remain disease-free for many years
after treatment. However, bone-specific side effects of
cancer therapies can have a negative effect on patients' long-term bone health. The accelerated bone loss associated with BC
therapies, especially endocrine
therapy, can put women at risk for
osteoporosis and fractures later in life. Recent treatment guidelines have now begun to address the need for bone-preserving measures to be included in adjuvant
therapy regimens.
Bisphosphonates have long been used to treat
osteoporosis, as well as bone
metastases in patients with advanced
cancers. Furthermore, in the adjuvant BC setting, the intravenous
bisphosphonate zoledronic acid has emerged to play an important role. Several large, randomized phase III trials involving a total of approximately 4,000 premenopausal and postmenopausal women with early BC demonstrated the bone-protective effects of adjuvant
zoledronic acid (4 mg every 6 months). Additionally, these same trials also showed significant improvement in disease-free survival for patients receiving adjuvant endocrine
therapy plus
zoledronic acid that was over and above the benefit achieved with endocrine
therapy alone. The results of these
zoledronic acid trials will be reviewed herein, and evidence supporting the antitumor effects of adjuvant
zoledronic acid will be discussed.