Different Targeting Strategies for Treating Breast Cancer Bone Metastases

Background: Breast cancer is the most frequently diagnosed malignancy in women worldwide. Breast cancer tends to metastasize to bone. Around 70% of the breast cancer patients eventually develop bone metastasis. After the bone invasion, metastatic cells disrupt the balance between osteoblastic and osteoclastic activities, leading to skeletal complications, characterized by pain and pathological fractures and hence worsening the patient's quality of life. Once tumor invades the bone, it is hard to treat it with, the so-far available treatments options (e.g. bisphosphonates and denosumab). Bone metastasis should be essentially controlled, in cancer treatment and there is a strong need to explore new, more efficient therapeutic targets. This review discusses the bone physiological processes and the recent advances in exploring different pathways involved in bone metastasis. Furthermore, some novel treatment options, which are under preclinical and clinical investigations, are highlighted. Conclusion: A deeper understanding of these metastatic pathways can provide oncology researchers with novel avenues for treating bone metastasis, one of the main challenges to cure breast cancer. The restoration of healthy bone environment will not only improve the patient's quality of life but also reduces the tumor burden.