Bone Cancer and Pain

Pain is the most common presenting symptom in patients with skeletal metastases. Two main types of cancer pain exist: ongoing pain, and incident or breakthrough pain. Pain is transduced at the level of the primary afferent nerve fiber that innervates peripheral tissue. Bone is densely innervated by sensory nerve fibers within the bone marrow, mineralized bone, and periosteum. Central sensitization, a heightened reactivity of nervous system in the face of sustained neural signals, can lead to allodynia, a painful condition where mechanical stimuli not normally perceived as noxious are painful. Proof of concept experiments showed that local anti-nerve growth factor (NGF) therapy can block ectopic sprouting and pathological reorganization of new nociceptive fibers, suggesting that prophylactic treatment may be capable of preventing bone cancer pain. Research is now focused on targeting pain initiation sites within the nervous system, namely, ion channels, cytokines and growth factors, to limit systemic complications.