Patients with bone colonized cancer frequently suffer from severe uncontrollable cancer-associated bone pain(CABP)during the course of illness. However, since current treatments do not satisfactorily control CABP and can elicit serious side effects, new therapeutic strategyies are needed to manage CABP. According to the recent study including ours, the cancer cell and osteoclast created-acidic extracellular microenvironment is expected to be therapeutic target for CABP.