Adjuvant bone-targeted therapy to prevent metastasis: lessons from the AZURE study

Bone-targeted treatments with bisphosphonates (e.g., zoledronic acid) and denosumab are known to reduce the risk of skeletal complications and prevent treatment-induced bone loss in patients with malignant bone disease. Additionally, these drugs may modify the course of bone destruction via inhibitory effects on the 'vicious cycle' of growth factor and cytokine signalling between tumour and bone cells within the bone marrow microenvironment.

In early stage breast cancer, treatment with zoledronic acid has shown improvements in disease-free and overall survival, notably in women with established menopause at diagnosis and in premenopausal women with endocrine-responsive disease, treated with goserelin to suppress ovarian function. Other bisphosphonates such as clodronate may produce similar benefits. Additionally, in castrate-resistant prostate cancer, treatment with denosumab delays the development of bone metastases.

These results strongly support the adjuvant use of bone-targeted treatments, but suggest that reproductive hormones are an important treatment modifier to take into account.