Stereotactic Body Radiosurgery: an Effective Treatment for Metastatic Spinal Tumors

To read a brief explanation of this study—and what it means for patients—click here.

Metastatic spinal tumors are the most common type of malignant lesions of the spine, accounting for approximately 70% of all spinal tumors.

Estimates indicate that at least 30% and as many as 70% of patients with cancer will experience the spread of cancer to their spine. Primary cancers that commonly spread to the spine are lung, breast, and prostate. Other cancers that spread to the spine include gastrointestinal tract, lymphoma, melanoma, kidney, sarcoma, and thyroid.

Non-mechanical back pain, especially in the middle or lower back, is the most frequent symptom of metastatic spinal tumors. Pain may spread beyond the back to the hips, legs, feet, or arms and may worsen over time—even when treated by conservative, non-surgical methods that may alleviate mechanical back pain. Pain and other symptoms may occur as the malignant tumor grows and compresses the spinal cord, nerve roots, blood vessels, or bones of the spine.

Researchers at the M.D. Anderson Cancer Center in Houston investigated the efficiency of stereotactic body radiosurgery (SBRS) in treating patients with cancer that metastasized to the spine. The results were published in the study Prospective Study of Cancer Control and Patient Reported Outcomes for Spinal Metastases treated with Stereotactic Body Radiosurgery.

Stereotactic radiosurgery (SRS) uses sophisticated image guidance to precisely target a narrow x-ray beam and deliver a highly-concentrated dose of radiation to the affected area. SBRS is a recent and emerging application of SRS to tumors in the spine, liver, lung, and other body sites. SBRS is generally delivered in a single or a small number of treatment sessions.

"The purpose of this study was to analyze the effectiveness of SBRS on cancer control and measure patient-reported outcomes in cases of spinal metastases," stated Dr. Chang, who co-authored the study.

One hundred twenty-one patients with cancers of the lung, breast, skin, kidney, colon, and connective tissues were enrolled over a five-year period from 2002 to 2007. There were 136 spinal metastases treated with SBRS. Tumor control was assessed using serial spinal MRI. Patient Reported Outcome (PRO) was assessed using validated instruments including the Brief Pain Inventory (BPI) and the M.D. Anderson Inventory (MDASI). Doctors use tests such as these to determine how much impact your pain has on daily functions. Comparing the pre-surgery results to those after surgery will show surgery's impact (if any) on pain.

The following results were noted:

• The 6-month and 1-year survival rate for spinal metastasis progression free survival (or PFS, which refers to the continuing presence but not progression of the disease) was 90% and 84%, respectively.
• The median survival for the study group was 21 months.
• Patient survival at 1-year follow-up was 65% and at 2-year follow-up was 42%.
• Using strict criteria for complete pain relief, the number of patients doubled who were completely pain-free at 3 months; at 6 months, post-SBRS compared to baseline.
• The five "most severe" symptoms prior to SBRS were fatigue, pain, sleep disturbance, drowsiness, and distress. At 6-month follow-up, significant reductions were seen in all of these symptoms.
• No cases of radiation myelopathy have been observed to date.
• Acute toxicities were manageable, and no late complications involving the spinal cord have been observed to date.

"In conclusion, SBRS in patients with spinal metastases is a safe and effective treatment modality, yielding high 6-month and 1-year PFS (progression-free survival) rates and dramatic reductions in pain and symptoms related to the metastatic cancer," Dr. Chang said.

Source:
American Association of Neurological Surgeons
Press Release: May 4, 2009

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