This article is more than 5 years old. Information may no longer be current.
Pain management of bone metastases requires multifaceted approach
Click Here to Manage Email Alerts
In cancers associated with bony metastases, bone destruction leads to increased pain, fractures and other skeletal events that result in morbidity and impaired quality of life. Although not all patients with metastatic bone disease exhibit symptoms, as many as two-thirds of these patients experience severe pain, especially those with advanced disease.
Bone pain was once thought to be merely somatic pain, but it is now understood to also contain neuropathic components, as well as a possible spinal cord-induced mechanism. When the tumor cells initially invade the bone, they release prohyperalgesic factors. As the tumor cells grow within the bone, sensory nerves that innervate the marrow are compressed and destroyed, which leads to a neuropathic component.
A newer described mechanism of metastatic bone pain, seen experimentally in mice, is an extensive neurochemical reorganization of the spinal cord segments that receive input from the areas of bone that contain tumors; this may be responsible for the allodynia some patients experience.
Methods of treatment
Treatment of metastatic bone pain should occur in a stepwise fashion. Initial treatment with an NSAID or an opioid is usually effective in the initial phase of invasion of the bone by tumor cells. The key is to find a schedule that achieves the best balance between adverse events and symptom relief. When adverse events start to outweigh the analgesia effects, opioid rotation or intrathecal therapy may be able to provide adequate relief.
|
|
For select cancers, such as metastases from lymphoma, myeloma and testicular neoplasms, systemic chemotherapy may also provide an analgesic effect. Similarly, patients with hormone-sensitive breast and prostate cancers may obtain relief from bone metastases with hormone therapy.
Radiotherapy for bone metastases is indicated for pain not alleviated with the above therapies; for those with nerve root pain or cranial nerve involvement; and for those at risk for pathologic fracture and neurological complications arising from spinal cord compression. Radiotherapy achieves pain relief by decreasing tumor size and accompanying inflammation; it may also initiate healing and reossification of lytic bone lesions. Numerous radiation therapy regimens may be employed, including fractionated and single-fraction regimens. Pain relief for patients is often effective when this regimen is combined with other approaches and can result in a decrease in the need for oral medication.
Radioisotopes, bisphosphonates
Radioisotopes are indicated for multifocal painful bone metastases and pain not controlled with conventional analgesic regimens. The three isotopes available in the US are strontium-89, samarium-153 and phosphorous-32. These compounds work by binding with high affinity to hydroxyapatite in the regions of rapid bone turnover near metastases and delivering therapeutic doses of localized beta radiation. The resulting analgesic effect may be caused by inhibition of lymphocyte-associated cytokines or alterations in osteoclast or osteoblast activity.
Bisphosphonates are used to treat cancer-related bone complications, including pain. They bind preferentially to bone at sites of active bone resorption and inhibit the recruitment and activation of osteoclasts. In the US, pamidronate, a second-generation compound, and zoledronic acid, a third-generation compound, are available. These medications have indicated to be most useful for breast cancer and multiple myeloma and, to a lesser degree, lung, gastrointestinal and prostate cancers. Both are administered as IV infusions. Within a week, 50% to 70% of patients achieve a 30% reduction in pain. The duration of relief averages 12 weeks.
Treatment of bone pain requires a multifaceted approach. A combination of radiotherapy, systemic treatment and supportive care is often beneficial to patients. The management approach should be tailored to the individual patient, based on his or her clinical condition, life expectancy and quality of life.
Christine A. Zawistowski, MD, is an assistant professor of pediatrics in the division of critical care at Mount Sinai Kravis Children’s Hospital, New York.