Efficacy of a single 5 mg zoledronic acid infusion in preventing bone loss and fracture in postmenopausal women with breast cancer

Chemotherapy-induced bone loss (CTIBL) is common among breast cancer patients, requiring comprehensive assessment and intervention. Zoledronic acid, a strong inhibitor of bone resorption, is effective in CTIBL management, though information on dosing and intervals, particularly the efficacy of the 5 mg annual dose for osteoporosis in breast cancer patients, is limited.

In this 12-month prospective observational study, 85 breast cancer patients were divided into three groups: 17 received no treatment, 17 received tamoxifen, and 51 received anastrozole or letrozole (AI). Post-surgery, patients were administered a single 5 mg dose of zoledronic acid and monitored over 12 months for changes in bone mineral density (BMD), fracture rates, and biochemical markers.

Initially, the AI group was the oldest, averaging 59.1 ± 8.7 years. At baseline, no significant differences in variables, except age, were observed. After 12 months, BMD increased in all groups following a single zoledronic acid dose, with the smallest increase in the AI group at the lumbar spine: no treatment (2.4% ± 6.1%), tamoxifen (2.6% ± 3.4%), AI (0.6% ± 14.5%) (p = 0.778). CTx and P1NP levels were consistently suppressed up to 12 months post-treatment, with smaller reductions in the AI group. There were no significant differences in fracture or bone metastasis rates among groups.

A single infusion of 5 mg zoledronic acid was effective in increasing bone density in breast cancer patients. However, AI-treated patients showed less improvement in vertebral bone mineral density and biochemical markers. Further long-term studies with larger cohorts are needed.