Therapy for relief of pain is customized for each patient depending on symptoms, the tumor of origin, and the bony area involved. It may include analgesics (pain-killers), biphosphonates, radiation, chemotherapy or hormone therapy, surgery or invasive pain management techniques. Combination therapy has been shown to improve overall pain control, and it reduces side effects compared with single therapy.
Radiotherapy
Radiation therapy is very effective for relieving localized bone pain. About 60% to 90% of patients will experience reduced pain, with approximately 50% getting complete relief of pain. However, repeat radiation may be limited because of side effects to the surrounding tissues, such as damage to the spinal cord after radiation of the bones of the spine.
Radiation may be used preventively in patients with bone metastases who, as yet, have no symptoms, to prevent progression of the metastasis itself. This approach is often considered for patients with vertebral metastases, since they are at high risk for spinal cord involvement.
Hormone treatment
Patients with certain hormone-dependent tumors such as breast, prostate, and endometrial tumors have shown benefit from hormonal therapy, which produces a slower progression of disease and a longer survival.
Orthopedic treatment
Some patients with bone metastases end up with fractures due to the thinness of their bones at the site of the bone metastasis. Surgical orthopedic treatment can help them maintain function. The femur (upper bone of the leg) is the most common site where this is done. Preventive orthopedic treatment involves surgical insertion of a pin to reinforce the bone, preventing a fracture from occurring.
When bone lesions are present in the vertebrae, spinal surgery can reduce pain, avoid neurological dysfunction, and increase mobility.
Analgesics (painkilers)
Analgesics remain the most widely used pain management treatment. The two categories of drugs generally used are the NSAIDs (nonsteroidal anti-inflammatory drugs) and the opioids.
- NSAIDs: These drugs are thought to be effective in relieving painful bone metastases because they inhibit the body's formation of chemicals called prostaglandins. Prostaglandins sensitize tissue and cause increased activity in pain-sensitive nerves. NSAIDS have also been shown to reduce the pain sensitization occurring in the spinal cord.
- Opioids: Opioids such as morphine are the main group of analgesic drugs used. These drugs act primarily in the brain and spinal cord, where they inhibit the transmission of pain impulses. No "ceiling" effect is evident - in other words, pain relief can always be reached with a high enough dose. The optimal dose is the dose that relieves pain without intolerable side effects. Pill form is the preferable route of administration. Opioids are also the primary drugs used to control "breakthrough" pain - situations where a higher-than-usual dose of pain-killer is needed.
Various opioids are formulated to be released slowly into the body. The goal is to maintain a constant, steady level of opioid in the body to control pain before it is felt. When opioid levels change, there are generally more side effects and poor pain control.
Drugs used in combination with analgesics
- Corticosteroids have potent anti-inflammatory properties. However, their effects are usually short-lived. These drugs are usually reserved for advanced disease, particularly where compression of the nerves is evident.
- Calcitonin reduces bone loss. It promptly reduces pain, but the effect is short-lived because tolerance to the drug develops, reducing its effectiveness.
- Bisphosphonates are taken up by the bone and inhibit bone loss, which in turn can reduce pain and prevent hypercalcemia.
- Radioisotopes such as strontium-89 and radioactive phosphate can be taken up by bone tissue to deliver radiation in patients in whom widespread metastases are present. Bone marrow toxicity limits their use.
Invasive techniques for relieving pain
Invasive techniques achieve pain relief by blocking or modulating the transmission of pain impulses along the nerves. This interruption of impulses can be done using peripheral nerve blocks, or spinal or epidural analgesia - these are technical procedures in which a needle is inserted near a nerve and local anesthetic agents are injected. These procedures stop pain messages reaching the spinal cord and can give complete relief by anesthetizing an area. The relief lasts only a short amount of time, however, so these techniques are most useful for obtaining rapid pain relief while other treatments are being begun.
The cutting of nerve pathways, such as with spinal or epidural neurolysis, or cervical cordotomy, are usually reserved for localized, uncontrolled pain associated with bone metastases. Also, removal of the pituitary and direct administration of opioid into the cerebrospinal fluid have been used for severe pain associated with bone metastases that are present in many parts of the body.