[Biological Features and Clinical Diagnosis of Bone Metastasis]

Bone metastasis could be developed in all cancer patients. Although practical registration of bone metastasis is not conducted, it is roughly estimated that tens of thousands of patients exist annually in Japan. Bone metastasis is highly detected in 30 to 90% of patients suffered from prostate, breast, and lung cancers. Cancer cells metastasize to bone through blood vessels, and the bone is destroyed mainly by osteoclast. Receptor activator of nuclear factor kappa-B ligand, which relates differentiation and maturation of the osteoclast is a therapeutic target at present. Physical symptoms of bone metastasis include pain, fracture, and paralysis. Worsened ADL and QOL of the patients additionally have negative impact on their psychosocial situation. Bone metastasis is diagnosed by symptoms based on the type of primary cancer, and confirmed by imaging measures such as CT, MRI, bone scintigraphy, and PET-CT.