Introduction:
The progressive approaches in cancer treatment have improved patient survival with advanced-stage cancers. As a result, it is often fatal due to bone metastases. Skeletal-related events, like pathological fractures and spinal paralysis, impair the quality of life. An early diagnosis and a preventive approach are required to avoid such serious skeletal-related events impairing the quality of life and survival. It is essential to start a bone management program along with cancer treatment to prevent complications of bone metastasis. Additionally, a multidisciplinary approach is required to focus on the management of bone metastases and involve a team of oncology specialists, radiotherapy, palliative care, nuclear medicine, radiology, physiatrists, and orthopedics. The focus should be on preventing complications arising from bone metastases and reducing morbidity, hospitalization, and costs associated with advanced-stage cancers.
What Is Bone Metastasis?
Metastasis is the spread of cancer cells to other body parts, and bone is one of the common sites of metastasis. Bone metastasis leads to morbidity in patients with advanced-stage malignant diseases. The advancements in cancer treatments, such as immune checkpoint inhibitors, and the development of molecular-targeted agents have improved the survival rate of people with advanced-stage cancers. Thus prolonging the clinical courses of individuals due to bone metastases. On the other hand, morbidities, such as spinal paralysis and pathological fractures, cause impaired daily life activities and quality of life and affect the prognosis because of deterioration of the patient's condition and discontinuation of treatment for the primary disease.
What Are the Supportive Therapies?
Painkillers:
Most cancer patients with bone metastases suffer from bone pain.Initially, nonopioid analgesic drugs, and nonsteroidal anti-inflammatory drugs (NSAIDs), were used for mild to moderate pain. However, if the pain is not relieved, these painkillers may be used in combination with an opioid. For moderate or severe cancer pain, opioids are the most common painkillers because they are effective for all types of cancer pain. In addition, most cancer patients with metastatic bone disease get adequate pain relief with opioids.
Osteoclasts Inhibitors:
Osteoclast inhibitors are used for treating metastatic bone disease in patients with solid tumors. Osteoclast inhibitors slow down the progression of skeletal metastases. Additionally, they also have a medium painkiller effect. However, the painkiller effect of all of these inhibitors is limited, and they are not recommended as first-line therapy to treat painful bone metastases.
Exercise:
People with bone metastases should be encouraged to engage in some form of physical activity. Studies have found that regular physical activity or exercise improves physical function and reduces the side effects related to treatment and cancer-related fatigue.
Anti-cancer Therapy:
Chemotherapy and hormone therapy may reduce pain by decreasing the tumor bulk or by altering the pain signaling pathways. Systemic therapy plays a major role in the treatment of prostate cancer with bone metastases. However, pain relief is usually not quickly achieved, and patients may find it difficult to tolerate chemotherapy. Chemotherapy may also cause painful side effects or complicated side effects, limiting the effective administered dose that can be administered. New drugs have fewer side effects and may be more tolerable. However, they are not associated with immediate pain relief.
What Are the Local Therapies?
Radiation Therapy:
External beam radiation therapy (EBRT) is a standard treatment option for symptomatic skeletal metastases, leading to 50 to 80 percent of pain reduction. Certain individuals with multiple bone metastases have pain that is not easily managed by local radiation. in such conditions, there are two options: hemibody radiation and bone-targeted radiopharmaceutical therapy. Hemibody radiation can provide quick pain relief at multiple sites of symptomatic bone metastases. It has been replaced for conditions such as advanced prostate cancer by bone-targeted radiopharmaceuticals, which cause pain relief and is associated with less toxicity.
Bone-targeted Radiopharmaceutical Therapy:
Bone-targeted radiopharmaceutical therapy is indicated in conditions like refractory bone pain despite painkillers, a positive bone scan, a life expectancy of more than three months, and no chemotherapy or bisphosphonate six weeks before treatment. Contraindications of bone-targeted radiopharmaceutical therapy include acute spinal cord compression, acute or chronic renal failure, pregnancy, breastfeeding, and myelosuppression (a condition that refers to a decrease in the production of blood cells in the bone marrow).
Surgical Management:
Surgical management of bone metastases is usually for lesions involving fractures. However, surgery might also be required for spine metastases causing mechanical instability or epidural spinal cord compression. Most patients without complete fractures or evidence of epidural spinal cord compression do not require surgery for bone metastasis. However, for individuals with advanced cancer with a bone lesion beyond the primary site, the entire resection of the metastasis may lead to tumor control, provide pain relief, and could prolong patient survival. However, curative removal is rare for bone metastasis, except for individuals with sternal involvement or isolated spine. For individuals with long bone or spinal metastases, postoperative radiation is generally given after surgical stabilization to promote bone healing, decrease pain, improve functionality, and reduce the risk for further fracture or fixation loss by treating the metastasis.
Ablation:
Thermal ablation is an essential therapeutic option for individuals with persistent pain in a few skeletal sites after radiation therapy and does not require surgery or re-radiation. The various ablation therapies, including cryoablation, radiofrequency ablation, and focused ultrasound, are effective treatments for reducing symptomatic skeletal metastases. During thermal ablation to vertebral metastasis, the treatment should be aimed at least 10 mm (millimeters) away from a neural structure to prevent neurological complications. Thermal ablation contraindications include the following:
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The inability of the individual to tolerate the level of anesthesia required to perform the procedure.
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Uncorrectable bleeding.
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Inaccessibility of the target lesion from a percutaneous approach.
The relative contraindications include the following:
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Widespread skeletal metastases.
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Active infection, or tumor located to an adjacent critical anatomical structure that cannot be displaced or precisely monitored to allow safe ablation.
Conclusion:
Bone is one of the recurrent sites of cancer metastasis. Prostate and breast cancer are responsible for the majority of bone metastases. The overall incidence of bone metastasis is unknown. Bone metastases lead to pathologic fractures, severe pain, impaired mobility, spinal cord compression, hypercalcemia, and bone marrow aplasia. In addition, bone metastases cause serious fatalities, such as pathological fractures and spinal paralysis, that hampers the quality of everyday life. The treatment strategies for bone metastases should be planned in such a way as to keep in mind the health status, prognosis, and social background of the individuals. Multidisciplinary approaches focusing on managing bone metastases should include specialists supporting comprehensive healthcare and treating individuals.
