Palliative Radiation Therapy For Bone Metastases

Bone is the site of metastases for many cancers during tumor pathogenesis. The incidence of new cases of bone metastases is estimated to be about 280,000 annually in the United States. Most notably, breast (65% to 75%), prostate cancer (65% to 90%), lung cancer (17% to 64%), and to a lesser extent, bladder cancer (40%), thyroid cancer (65%), melanoma (14% to 45%), kidney cancer (20% to 25%), and colorectal cancer (10%) favor metastases to the bone. Multiple myeloma accounts for about 70% to 95% of bone lesions. The structural bone damage that ensues leads to significant pain, pathologic fractures, and decreased quality of life. Metastasis can occur in 3 main anatomic locations: the extremities, pelvis, and spine. The most common site of metastatic bone lesions is the spine. The most common location is the thoracic spine (60% to 70%) of the spinal columns. The lumbosacral spine accounts for 20% to 25%, followed by the cervical spine with 10% to 15% of spinal metastasis. The upper extremity accounts for about 24%, whereas the lower extremity accounts for about 76% of the long bone metastases. The primary reason for treating bone metastases is to prevent further skeletal injury and improve symptoms. Generally, surgical treatment options are offered to patients with a life expectancy greater than 6 weeks. Those with a life expectancy of 3 to 12 months are treated with minimally invasive surgery. En bloc resection of metastatic lesions may be the best option for patients with a life expectancy of 12 months or more. For patients who do not fall into the surgical treatment category, palliative radiation therapy of the bony metastases is a viable treatment option.