Metastatic Tumors to the Spine
Many cancers that arise outside of the spine or spinal cord can travel to the area surrounding the spine. Tumors around the spinal bones (vertebrae) can cause pain and, on occasion, collapse of the vertebrae. These tumors also can 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 those patients have symptoms from their spinal metastases. 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
Most patients who develop symptoms from metastatic tumors to the spine experience pain. The pain may be mild at first and is often mistaken for arthritis or a mild back strain. It may be treatable initially with acetaminophen or ibuprofen but may become more constant and severe over days or weeks.
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
There are three major reasons why cancer involving the spine may cause pain, and knowing the cause of the symptoms is 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 with radiation or chemotherapy might relieve the symptoms completely.
The second reason for pain is when the tumor destroys enough of a vertebra to break the bone. If the break is mild, destroying the tumor may relieve the pain and the bone can heal. However, if the break is severe and the vertebra collapses, then killing the tumor may not relieve the pain and symptoms may even get worse despite the tumor not being present anymore. This often requires surgery to treat the pain.
The third 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 but little or no destruction of the vertebra from spinal metastases, chemotherapy or, in most cases, radiation therapy is all that is required. Myeloma, breast, prostate and some types of lung cancer are usually sensitive to radiation, whereas renal cell cancers, melanoma and most sarcomas are not. For patients with tumors that are not sensitive to radiation or who have severe destruction of the vertebra with or without compression of the spinal cord, surgery followed by radiation is usually necessary.
New treatment options are available for patients with radiation-insensitive tumors, those who have failed radiation and those who are not able to undergo surgery. Stereotactic radiosurgery at the CyberKnife® Center is very useful in treating cancer of the spine as it targets the cancer precisely while avoiding the spinal cord. The treatment involves placing small markers near the spine in an outpatient procedure. 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 been shown both in patients who have previously failed radiation and in those with radiation-resistant tumors. Stereotactic radiosurgery now provides patients with metastatic tumors to the spine with more effective and less invasive alternatives for treatment.