May 06, 2015

Washington, DC — The use of a magnetic resonance (MR)–guided laser ablation technique shows success as a minimally invasive alternative to separation surgery in high-grade malignant spinal cord compression, a new study on the technique suggests.

"This is a good, minimally invasive alternative to surgery for patients with a high surgical risk," said Claudo Tatsui, MD, a neurosurgeon with the University of Texas MD Anderson Cancer Center, Houston, Texas, in presenting the findings here at the American Association of Neurological Surgeons (AANS) 83rd Annual Meeting.

Whereas spinal metastases are typically managed with invasive, open surgery to remove the epidural tumor, followed by stereotactic spinal radiosurgery (SSRS), laser interstitial thermotherapy represents a potentially useful alternative.

"Instead of opening the space and performing an extensive surgery, we are proposing interstitial laser therapy, applying the laser in the space close to the junction of the tumor and the spine and monitoring the temperature with magnetic resonance thermometry," Dr Tatsui explained.

"Once the temperature reaches this threshold (of about 50°C), the system stops and then we can protect the spinal cord."

Dr Tatsui shared his experience with the technique among 14 patients with a high degree of epidural compression resulting from radio-resistant tumors. The median follow-up was 28 weeks (range, 10 to 64 weeks).

The procedure specifically involved positioning the laser probe with standard spinal image guidance. Real-time MR sequences and anatomic T2 images were used to monitor the tissue temperature and damage in the area of ablation. The patients all then underwent postoperative SSRS.

With a median visual analogue pain score of 6 before surgery, the median scores after the procedure dropped to 3 within 30 days and to 2 within 60 days of treatment.

Quality-of-life scores meanwhile increased from 49% before surgery to 63% at 30 days and 61.5% at 60 days.

Improvements in the degree of spinal cord compression were observed on imaging in 12 of the 14 patients at the follow-up 2 months after the procedure.

"We believe there is a synergistic effect between the laser ablation and the stereotactic radiation with this approach," Dr Tatsui said.

Relative Benefit

The decision to pursue surgery is typically considered in the context of poor survival expectation in the population of patients with metastatic tumors involving the spine, said Clark C. Chen, MD, PhD, an associate professor of neurosurgery and vice chair of research and academic development at the University of California, San Diego. 

"Historically, surgical treatment of these tumors involves large incisions and prolonged recovery period," he explained to Medscape Medical News.

"[But] let's say the survival expectation is 3 months, and the anticipated recovery from surgery is 1 month — what is the relative benefit of surgery? We, as surgeons, need to discuss this issue with the individual patient in order to arrive at a treatment plan that is optimized for the patient."

"The reported [laser] surgery approach minimizes the time of recovery and offers neurosurgeons another option in this decision making process," he said.

"The recovery period associated with laser thermal ablation is typically on the order of days and not weeks or months."

Dr Chen noted that he has had success treating brain tumors with laser thermal ablation, using the same technology that Dr Tatsui employed to treat spinal tumors, and said MR thermometry has been key advancement that ensures the safety of treatment. 

"MR thermometry is an extraordinary technology that allows us to determine the temperature of the tissue inside our body in real time," he said. "In doing so, the technology allows the surgeon to determine how far the heat from the laser has propagated and to stop the laser before it adversely affects the normal tissue."

"There are more extended experiences in laser thermal ablation of brain tumors, but to my knowledge, this is the first report of its application to spinal tumors," he added.

"While these results are preliminary, the study is very interesting and the approach has the potential to reshape the treatment strategies for patients afflicted with spinal metastasis."

Dr Tatsui has disclosed no relevant financial relationships. Dr Chen has consulted for Monteris and Clearpoint and received an honorarium from Varian.

American Association of Neurological Surgeons (AANS) 83rd Annual Meeting. Abstract 616. Presented May 4, 2015.

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