The spinal column is the most frequent site of bone metastasis in the body. Breast, lung, prostate, and renal carcinoma are the most common tumors that disseminate to the spine. Spinal metastasis from myeloma, lymphoma, and gastrointestinal carcinoma are also common; however, these occur less frequently. Approximately 18,000 new cases of spinal metastatic disease are diagnosed each year in North America alone. Evaluation at a spine center usually occurs for patients who have intractable pain or spinal cord compression caused directly or indirectly by the metastatic disease. Advances in spinal surgery have allowed frontline therapy utilizing surgical reconstruction to be more feasible and more effective. Anterior approaches to the spine allow direct access to the metastatic lesion, reconstruction of the anterior vertebral column, and the placement of anterior instrumentation. Outcomes have substantially improved with surgery in addition to radiotherapy rather than radiotherapy alone. In select patients, surgery may be desired as first line therapy before radiotherapy or chemotherapy has been initiated. Although the cost of surgical intervention is high, the medical costs of tumor-induced paresis or paraplegia is much higher.
The treatment goals of anterior, lateral and posterior approaches include the decompression of neural elements and reconstruction of the weight-bearing spinal column. The ultimate goal in metastatic disease is not fusion, but spinal stability achieved by placing instrumentation and struts. In this regard, titanium cages are often used as interbody struts and often a bone graft is not placed. Spinal instrumentation and interbody struts are utilized to confer spinal stability for the remainder of the patient’s life, which is often significantly shorter than the time required to achieve a solid fusion. Cement is often used in the place of bone graft, to provide immediate stability.
Outcomes are generally good with motor function having been found to improve in greater than 70 percent of patients and pain improving almost uniformly. Wound-related complications are higher in the posterior approaches after radiation but the wound-related complication rate for anterior approaches is approximately three percent.
In light of greater comfort with anterior approaches, dramatic improvements in spinal instrumentation, and increased understanding of the pathophysiology of spinal metastasis, surgery should be offered as first line therapy as opposed to a salvage operation in many patients. Patients with spinal metastatic disease should be referred early on to a spinal center for evaluation.
MD News October 2008