An update on the currently available and future chemotherapy for treating bone metastases in breast cancer patients

Bone metastases in breast cancer patients are a common clinical problem. Many factors influence the treatment decision, including tumor characteristics, previous treatment and tumor burden in the treatment of metastatic breast cancer.

This present review summarizes the new treatment strategies and the chemotherapeutic agents currently available in the management of metastatic breast cancer with bone metastases.

Patients with bone metastases more often have hormone receptor-positive tumours. Although new treatment agents for metastatic breast cancer have been investigated, endocrine therapy is still considered as the treatment of choice for patients with bone metastases although chemotherapy still has an important place. In recent years, new chemotherapeutic agents such as etirinotecan and nab-paclitaxel have been established though there are few studies that have looked at particular types of metastases. In the last decade, therapies for bone metastasis resistant to endocrine therapy have predominantly focused on radiotherapy, surgical resection, chemotherapy, bone-targeting radiopharmaceuticals and targeted therapeutics. New targeted agents include: Src inhibitors, cathepsin K inhibitors, CXCR4 inhibitors, TGF-B blockade and integrin antagonists while drug delivery systems for chemotherapy have also been developed. These new treatment options could be future treatment options for bone metastatic disease if early promising results are confirmed by clinical trials.