Bone Pain
Bone pain in patients with cancer is commonly caused by cancer cells that have spread to the bones, called bone metastases. Bone pain is commonly the first symptom of bone metastases and may lead to tests that will confirm the diagnosis. Treatment for bone pain is intended to relieve the pain, treat fractures, reduce the risk of fracture, and prevent or delay additional bone complications. Treatment options include pain medications, bisphosphonate drugs, radiation therapy, and/or surgery.
- What causes bone pain?
- How are bone metastases diagnosed?
- How is bone pain treated?
What Causes Bone Pain?
A common cause of bone pain is metastatic cancer. The spread of cancer from its site of origin to another location in the body is called metastasis. A bone metastases is not a new cancer, but consists of cancer cells from the original cancer, such as breast, prostate, lung, kidney, or thyroid, that have spread to bone.
Cancer cells can spread, or metastasize, through the blood and lymph systems. Bone is one of the most common locations in the body to which cancer metastasizes. Bone metastasis usually occurs by way of the bloodstream. A cancer cell may break away from the original location in the body and travel in the circulatory system until it gets lodged in a small capillary network in bone tissue. Cancer may also spread to bone by erosion from the adjacent cancer, though this occurs less frequently than spread by the bloodstream.
The pain occurs with bone cancer because the cancer disrupts the balance of normal cellular activity in the bones, causing damage to the bone tissue. Normal bone is constantly being remodeled, or broken down and rebuilt. Cancer cells that have spread to the bone disrupt this balance between the activity of osteoclasts (cells that break down bone) and osteoblasts (cells that build bone), resulting in either weakened or excessively built-up bone. This damage can either stretch the periosteum (thick membrane that covers bone) or stimulate nerves within the bone, causing pain.
How are Bone Metastases Diagnosed?
Bone metastases are usually diagnosed because the patient experiences pain near the metastases and reports this to their doctor. The doctor may then complete an x-ray or a more complicated procedure called a bone scan to confirm that the pain is caused by cancer-related damage to the bones. In a bone scan, low level radioactive particles are injected into a vein. They circulate through the body and some are absorbed into the bones. A high concentration of these radioactive particles on the bone scan results indicates the presence of rapidly growing cancer cells in the bone.
Bone pain may be hard to differentiate from ordinary low back pain or arthritis. Usually the pain due to bone metastasis is fairly constant, even at night. It can be worse in different positions, such as standing, which may compress the cancer in a weight bearing bone. If pain lasts for more than a week or two, doesn’t seem to be going away, and is unlike other pain that may have been experienced, it should be evaluated by a physician.
Bone metastases generally occur in the central parts of the skeleton, although they may be found anywhere in the skeletal system. Common sites for bone metastases are the back, pelvis, upper leg, ribs, upper arm, and skull. More than 90% of all metastases are found in these locations.
How is Bone Pain Treated?
The goal of treatment for bone pain caused by bone metastases is to relieve the pain, treat fractures, reduce the risk of fracture, and prevent or delay additional bone complications. Treatment options for bone metastases include pain medications, bisphosphonate drugs, radiation therapy, and/or surgery.
Pain medications: Cancer-related bone pain can be managed with various pain medications. Despite the claim that 90% of adult cancer patients’ pain can be relieved, uncontrolled cancer-related pain is still a concern, particularly for patients who are living at home. Research presented at the 2003 Annual Meeting of the Oncology Nursing Society indicates that most cancer patients are not prescribed enough medication to control their pain.
The World Health Organization recommendations for relief of cancer pain indicate that the severity of a patient’s pain, rated on a scale of 1-10, will dictate what type of pain medication is used.
- Mild to Moderate Pain (1-3): Non-opioids are the first choice of treatment for mild to moderate pain. This includes medication such as acetaminophen (Tylenol®) or a non-steroidal anti-inflammatory drug (NSAID), such as ibuprofen.
- Moderate to Severe Pain (4-6) Patients with moderate to severe pain who have not responded to the first step should receive an opioid. These medications may include codeine, hydrocodone, dilhydrocodiene, oxycodone, propoxyphene, and tramadol. Acetaminophen or a NSAID may be added.
- Severe Pain (7-10) Patients with severe pain or patients whose pain has not been relieved by the previous recommendations will usually receive a stronger opioid. Opioids for severe pain may include morphine, oxycodone, hydromorphone, methadone, levophanol, or fentanyl. A non-opioid medication such as aspirin, acetaminophen, or ibuprofen may be added in some cases.
Pain medications may have side effects, including sleepiness, constipation, dizziness, nausea, and vomiting. Relief from pain medications is temporary and the pain may return in a short time; thus, medications are best used at the onset of pain or at regular intervals.
Bisphosphonate Drugs
Bisphosphonate drugs can effectively prevent loss of bone that occurs from metastatic lesions, reduce the risk of fractures, and decrease pain. Bisphosphonate drugs work by inhibiting bone resorption, or breakdown. Bone is constantly being “remodeled” by two types of cells: osteoclasts, which break down bone; and osteoblasts, which rebuild bone. Although the exact process by which bisphosphonates work is not completely understood, it is thought that bisphosphonates inhibit osteoclasts and induce apoptosis (cell death) in these cells, thereby reducing bone loss. There is also evidence that these drugs bind to bone, thereby blocking osteoclasts from breaking down bone.
Cancer cells release various factors that stimulate osteoclastic activity, causing increased breakdown of bone. By inhibiting osteoclasts, bisphosphonate drugs effectively reduce the detrimental impact that cancer cells have on bone density. An analysis of the results from 30 clinical trials demonstrates that patients with bone metastases treated with a bisphosphonate had a delayed time to skeletal fractures, a reduced need for radiation therapy to treat bone metastasis, a reduction in hypercalcemia (high blood levels of calcium), and a reduction in the need for orthopedic surgery
Bisphosphonate drugs that are FDA-approved for the treatment of cancer-related skeletal complications include Zometa® (zoledronic acid) and Aredia® (pamidronate). Of these two drugs, Zometa® appears to demonstrate the strongest activity. An added benefit of Zometa® is that it is administered in a dose ten times lower than Aredia®, which considerably reduces the administration time from several hours to 15 minutes, resulting in a more convenient regimen for patients.
Bisphosphonates have been shown to prevent or delay bone destruction and related pain in clinical trials involving patients with bone metastases related to:
Breast cancer: Bisphosphonate therapy has been shown to prevent or delay bone destruction and related pain in women with breast cancer that has spread to the bone. In a large clinical trial, a total of 751 women with metastatic breast cancer were randomly assigned to receive the bisphosphonate drug, Aredia®, or placebo (inactive substitute). The results showed that 64% of women who received the placebo had significant bone damage, compared with only 51% of those who received the bisphosphonate. The average time to the occurrence of the first bone complication was 13 months in the bisphosphonate group, compared to only 7 months in the placebo group. Furthermore, women who did not receive the bisphosphonate experienced significantly more pain and received more pain medications.
Learn more at the Breast Cancer Information Center
Prostate cancer: Zometa® has been shown to be a safe and effective treatment in prostate cancer patients with bone metastases. Zometa® significantly reduces the proportion of patients who experience skeletal complications, extends the time to first skeletal complication, and reduces the risk of skeletal complications.
Zometa® also appears to benefit patients with prostate cancer undergoing androgen deprivation therapy, or “hormonal therapy”. Hormonal therapy in the treatment of prostate cancer has been shown to cause bone loss.
Researchers from Massachusetts General Hospital and 5 other medical institutions conducted a clinical trial evaluating Zometa® in patients with localized prostate cancer being treated with androgen deprivation therapy. This study included 106 men who were randomly selected to receive either Zometa® or a placebo for one year. Bone mineral density in the spine, hips, and legs increased among patients who were treated with Zometa® and decreased in patients who received placebo.
Learn more at the Prostate Cancer Information Center
Lung cancer: Zometa® is a safe and effective treatment for bone metastases associated with lung cancer. In a clinical trial, 773 patients with lung cancer were randomly assigned to receive Zometa® or placebo via a 15-minute infusion every 3 weeks for 21 months. Results from the two groups were directly compared and showed that the number of patients experiencing at least one skeletal-related event was lower among those who were treated with Zometa® (39%) than patients who received placebo (46%). The patients who received Zometa® went nearly 3 months longer without developing a skeletal-related event and also experienced fewer skeletal-related events.
Learn more at the Non-Small Cell Lung Cancer Information Center
Multiple myeloma: A major complication suffered by patients with multiple myeloma is destruction of the bones, causing fractures and pain. A comparison of treatment with chemotherapy plus the bisphosphonate drug Aredia® to chemotherapy alone showed that patients who received the bisphosphonate had fewer bone fractures and decreased pain. In addition, some patients lived longer./p>
Research indicates that Zometa® is as effective as Aredia®. Among 1,648 patients with multiple myeloma or advanced breast cancer who had at least one bone lesion, pain and the use of pain medication was decreased with both treatments. However, patients who received Zometa® experienced significantly less need for radiation therapy to treat bone complications.
Learn more at the Multiple Myeloma Information Center
Renal cell carcinoma: Researchers from Pennsylvania have reported that Zometa® improves outcomes and reduces skeletal-related events in patients with renal cell carcinoma and associated bone metastases. The researchers analyzed data from 74 patients with renal cell carcinoma who were involved in a larger trial that involved patients with other types of cancers. Patients with renal cell carcinoma may be at a greater risk for developing skeletal-related events than patients with other types of solid cancers. The proportion of patients with renal cell carcinoma was nearly twofold greater than the proportion of patients in the entire population (44% vs. 74%).
The patients were treated with Zometa® or placebo (inactive substitute) and compared for the development of skeletal-related events, which included bone fracture, spinal cord compression, or the need for radiation or surgery for the treatment of bone metastasis.
Patients treated with Zometa® had a 61% reduced risk of developing a skeletal-related event than those who received a placebo. Also, the patients who received Zometa® had less cancer progression in their bones and lived longer.
Surgery: When there is an immediate or significant risk of fracture, surgery may be necessary to stabilize the weakened bone. Metal rods, plates, screws, wires, nails, or pins may be surgically inserted to strengthen or provide structure to the bone damaged by metastasis.
