Targeting bone metastases starting from the preneoplastic niche: home sweet home

The metastatic process is a multistep coordinated event with a high degree of efficiency. Specific subpopulations of cancer stem cells, with tumor-initiating and migratory capacity, can selectively migrate towards sites that are able to promote survival and/or proliferation of metastatic tumor cells through a microenvironment modification. Cross-talk between the bone microenvironment and cancer cells can facilitate bone tropism of cancer cells. Fully understanding this complexity represents a major challenge in anti-cancer research and a mandatory step towards the development of new drugs potentially able not only to reduce the consequences of bone lesions but also to target the metastatic process in visceral sites.