Pain management is an important part of the treatment of any disease state, and this is particularly true in the case of metastatic cancer. Due to the social stigma sometimes associated with taking pain medications and the potential risks involved with its continued use, patients and prescribers may shy away from using them extensively.
This is usually not a problem for patients with cancer, as prescribers are aware of their acute and chronic pain and prescribe pain medication appropriately. However, there are still factors that can interfere with optimal pain management.
Correct diagnosis of pain is crucial to its management. In order to correctly diagnose pain, it is important to be able to distinguish different types of pain. Somatic pain is usually in one specific location and it is characterized as being sharp, aching, and throbbing.1 Neuropathic pain can cause tingling, burning, and numbness.1 Visceral pain is more difficult to pinpoint as it may feel like a consistent dull ache, which is often what occurs with bone metastases.1 Metastatic cancer cells damage bones and cause pain by activating osteoclasts, which dissolve and weaken bones.2 They can also make certain areas of the bone harder, causing sclerosis.2
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Patients with bone metastases can often have short or shooting pains from the body through the bones in the arms and legs.3 This pain can worsen at nighttime or with increased activity, depending on which bones are affected.3 Inappropriate diagnosis and/or management of pain can lead to negative consequences including chronic pain, sleep disturbances, decreased mobility, and decreased socialization.
There are many different options used for pain management in patients with bone metastases. Pharmacologic therapy includes non-opioids such as nonsteroidal anti-inflammatory drugs for mild pain, weak opioids with or without non-opioids for moderate pain, and stronger opioids for severe pain. Epidural administration of medications should be considered in some cases as this area contains the nerves that are responsible for the majority of pain signals.
Nonpharmacologic therapy should play an important role because it can lead to superior pain relief and reduction of analgesic consumption. External beam radiation has been established through numerous trials to be effective when treating pain by using a machine to target a high energy beams at cancer cells.4 The overall response rate of patients in a prospective study improved significantly and peaked at day 8 after completion of treatment.4 Patients responding to the treatment at day 8 had a longer pain relapse–free survival as well.4
Another medical treatment for cancer-related bone pain includes radiopharmaceuticals. Internal therapy with radionuclides is used to control pain and improve quality of life. In one case study, treatment with radionuclide strontium-89 chloride (89Sr) resulted in successful relief of pain.5 The results of the report indicate that radionuclide therapy using 89Sr is an effective and well-tolerated palliative treatment in patients with bone metastatic prostate cancer.5
Biphosphonates can be useful for bone metastatic pain as well, especially in poorly localized, non-mechanical bone pain. Currently, two of these drugs have indications for this specific use. Zoledronic acid is indicated for multiple myeloma and bone metastases from solid tumors.6 Pamidronate is used for osteolytic bone metastases/lesions.6 Most patients who use bisphosphonates for bone pain do so because of skeletal metastases from advanced breast cancer.7 Randomized controlled trials of intravenous pamidronate, clodronate, ibandronate, and zoledronate have all demonstrated useful pain relief and have shown that long-term bisphosphonate treatment is effective in reducing skeletal morbidity in breast cancer with fewer skeletal-related events, reduced pain and analgesic consumption, and improved quality of life.7
Other treatments for managing pain include denosumab, which prevents breakdown of the bone by inhibiting the protein RANKL,3 and calcitonin, a synthetic hormone given as an injection.
Cancer-related pain management in patients with bone metastases is a crucial element of their treatment and necessary to improve quality of life. Proper diagnosis of the type and exact location(s) of pain is necessary to determine appropriate treatment. A multi-faceted approach combining pharmacologic and nonpharmacologic therapy should be used to meet the needs of each individual, as there is no particular standard therapy that is applicable to all patients. This is why proper diagnosis becomes so important; it allows prescribers to make individualized regimens for their patients.
References
1. Pain types. Pain Clinic Web site. http://www.painclinic.org/aboutpain-paintypes.htm. Accessed April 1, 2013
2. Bone Metastasis. American Cancer Society Web site. http://www.cancer.org/acs/groups/cid/documents/webcontent/003087-pdf.pdf. Accessed April 1, 2013
3. Managing pain related to cancer and bone. Bone and Cancer Foundation Web site. http://www.boneandcancerfoundation.org/pdfs/Pain_2011.pdf. Accessed April 1, 2013
4. Truntzer P, Atlani D, Pop M et al. Early evaluation predicts pain relief of irradiated bone metastases: a single-center prospective study. BMC Palliat Care. 2013 Mar 13;12:12.
5. Zhang W, Zhao W, Jia Z et al. Strontium-89 therapy for the treatment of huge osseous metastases in prostate carcinoma: A case report. Exp Ther Med. Feb 2013; 5(2): 608–610
6. Biphosphonates. Drug Facts and Comparisons. Facts & Comparisons [database online]. St. Louis, MO: Wolters Kluwer Health, Inc; 2013. Accessed Apr 1, 2013
7. Coleman R. Management of Bone Metastases. The Oncologist. Dec. 2000; 5(6): 463-470.
