Bone pain represents one of the most debilitating side effects of the metastases of high-incidence cancers such as breast, prostate, lung, and multiple myeloma (myelomatosis). Severe bone pain is frequent, reported by greater than 65% of patients suffering with bone metastases. The most common sites affected include the pelvis, femur,
skull, and vertebra. The patient often describes the pain as dull and aching, localized at the site affected; however, some patients experience short, shooting pain that radiates out from the torso to the extremities. Movement typically aggravates the pain. Bone pain can signal disease progression, a new infection, or a complication from treatment. Pain is a reliable early indicator of complications from metastases-osteoporosis, hypercalcemia, fractures, and spinal cord compression. These conditions not only adversely affect the patient's quality of life, but in some cases may create such a decline that death results not from the metastases, but solely from bone-and skeletal-related complications. Patient complaints of bone pain require diagnostic confirmation, usually by radiographic techniques. Plain-film radiography may adequately detect typical lesions from metastatic causes, but may not be sensitive enough to detect certain complications. In these cases, radionuclide scintigraphy and magnetic resonance imaging (MRI) are the preferred diagnostic tools.
Causes
Bone pain may be the result of direct tumor involvement. Pain is produced when the tumor infiltrates the skeletal structures. The tumor may compress surrounding blood vessels, nerves, and soft tissue, or may be activating nociceptors (pain receptors) located at the site. Pain may also be a result of tissue compression caused by fibrosis (a condition caused by an increase in tissue) after the patient has undergone radiation therapy; this type of bone pain tends to be tolerable. A predominant source of bone pain in the cancer patient is due to pathologic fracture and to osteoclast-induced bone resorption by the tumor. This condition promotes bone loss and, at the same time, provides growth factors for the tumor to increase in size.
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