Metastatic Tumors to the Spine
Many cancers that arise outside of the spine or spinal cord can travel to the area surrounding the spine. These tumors can travel to the spinal bones (vertebrae), causing pain and, on occasion, collapse of the vertebrae. These tumors can also affect the soft tissues and spaces surrounding the spine (the epidural space) and compress the spinal cord or the spinal nerves, resulting in pain, paralysis, sensory loss, and/or loss of bowel or bladder control. All of these areas of tumor spread are termed "metastatic disease of the spine" or "spinal metastases." Even though the cancer now affects the spine, the cells are still from the primary tumor (breast, lung, colon, etc.) and therefore the treatment of spinal metastases depends on the type of tumor, number of tumors and the amount of systemic disease.
Incidence
The spine is the most common location of metastatic disease and is involved in about 70 percent of patients who have cancer. However only about 10 percent of all cancer patients will have symptoms from their spinal metastases during their lifetime, with the rest having cancer in their spine but not having major problems from it. In spite of that, there are still about 18,000 new cases of spinal metastases diagnosed each year. For the patients who do develop symptoms, understanding the treatment options and choosing the most appropriate one can be very stressful and confusing.
Symptoms of spinal metastases
Most patients who develop symptoms from their metastatic tumors to the spine first experience pain. The pain may be mild at first and often mistaken for arthritis or a mild back strain. It may be treatable initially with acetaminophen or ibuprofen but will generally progress in severity over days or weeks, becoming more constant and severe. Other patients will have only minimal pain and then one day experience a rapid increase in symptoms often with little or no provocation. Some patients with cancer in their chest area will experience pain wrapping around their chest, while those with cancer in the lower spine may experience pain running down their leg. Some patients will experience only pain, while others may also suffer from weakness in their arms or legs. The weakness may be mild or may progress to paralysis in a relatively short period of time.
Causes of pain from spinal metastases
There are three major reasons why cancer involving the spine may cause pain for the patient, and knowing the cause of the symptoms may be important for determining the most appropriate form of treatment. Pain may be caused by a tumor replacing the bone marrow in the bodies of the spine. At this point killing the tumor in the area byn radiation or chemotherapy might completely relieve the symptoms. The second reason for pain is when the tumor destroys enough of the vertebra to cause either a mild or a severe break in the bone. If the break is mild, destroying the tumor may relieve the pain as the bone may then heal. However, if the break is severe (and the vertebra collapses), then killing the tumor may not relieve the pain, and symptoms may persist and get worse in spite of the tumor not being present anymore. This often requires surgery to treat the pain. The other cause of pain (and in some cases weakness or paralysis) is when the cancer grows out of the bone and puts pressure on the spinal cord. If the pressure is mild, then killing the tumor may be all that is necessary, but in more severe cases surgical decompression by removing the tumor may be necessary.
Treatment
For patients with pain and little or no destruction of the vertebra from spinal metastases, treatment with chemotherapy or, in most cases, with radiation therapy is all that is required if the patient has a tumor that is sensitive to radiation. Myeloma, breast, prostate and some types of lung cancer are usual sensitive to radiation, whereas renal cell cancers, melanoma and most sarcomas are not sensitive to the usual doses of radiation. For patients who have radiation insensitive tumors or who have severe destruction of the vertebra with or without compression of the spinal cord, surgery followed by radiation is usually necessary.
CyberKnife® treatment of spinal metastases
New treatment options now are available for patients with radiation insensitive tumors, those who have failed radiation and those who are not felt to be able to undergo surgery. Stereotactic radiosurgery with the CyberKnife® is very useful in the treatment of cancer of the spine as it allows precise targeting of the area of cancer while avoiding the spinal cord. The treatment only requires placing small markers near the spine in a procedure done on an outpatient basis. The actual treatment is done in one, two or three sessions taking about 60 minutes each. Patients go home the same day, and the treatment causes no pain. Excellent results have now been shown both in patients who have previously failed radiation and in those with radiation resistant tumors such as sarcoma and renal cell cancers. Stereotactic radiosurgery now provides patients with metastatic tumors to the spine with more effective and less invasive alternatives for treatment.
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