Pros and Cons of Alpha versus Beta Bone Seeking Agents in the Treatment of Cancer Pain

Skeletal metastases occur in many types of solid malignant tumors, especially in advanced stage of prostate, breast, and lung cancers. The resulting bone pain affects patient's quality of life and requires effective treatment. Only osteoblastic bone metastases are suitable for treatment with bone-seeking agents. Typical tumors are prostate cancer with 65 to 85% of bone metastases, breast cancer with 65 to 75%, and small cell lung cancer with 34 to 50%, respectively.[1] The mechanisms involved in bone pain are poorly understood,[2] but are likely to be a consequence of osteolysis (bone breakdown).[3] Infiltration of the bone trabeculae and matrix by tumor osteolysis is one of the physical factors. Pain may result from instability-based microfractures and stretching of the periosteum by tumor growth.[4] The pathophysiological mechanisms of pain include stimulation of free nerve endings in the endosteum by a variety of chemical mediators like bradykinin, prostaglandin, histamine, interleukin, and tumor necrosis factor.[4] [5]