In the news – article excerpt:

Mayo Clinic Finds Early Success with Laser That (Ablates) Tumors with Heat

Thursday, October 14, 2010

JACKSONVILLE, Fla. — Physicians at Mayo Clinic’s Florida campus are among the first in the nation to use a technique known as MRI-guided laser ablation to heat up and destroy kidney and liver tumors … the physicians say (it) is potentially beneficial against most tumors in the body — either primary or metastatic — as long as there are only a few in an organ and they are each less than 5 centimeters in size (about 2 inches in diameter). Patients also cannot have a pacemaker or certain metallic implants, since the procedure is done inside an MRI machine.

“We believe there are a lot of potential uses of this technique — which is quite exciting,” says Eric Walser, M.D., an interventional radiologist… at Mayo Clinic, Florida.

In the United States, laser ablation is primarily used (in) brain, spine and prostate tumors, but is cleared by the U.S. Food and Drug Administration (FDA) for any soft tissue.

…many of whom (patients) are on a liver transplant waiting list. The clinic is a large liver transplant center, and a number of patients with cirrhosis have small tumors in their liver. “We (ablated) the tumors to keep them at bay because we could not use chemotherapy in these patients, who are quite ill and are waiting for a new liver,” he says. He also adapted it for use in (ablating) kidney tumors.

The outpatient procedure is performed inside an MRI machine, which can… monitor temperature inside tumors. A special nonmetal needle is inserted directly into a tumor, and the laser is turned on to deliver light energy. Physicians can watch the temperature gradient as it rises, and they can see (it) in the organ where the heat is. When the tumor and a bit of tissue that surrounds it (which may harbor cancer cells) is heated to the point of destruction — which can be… seen on monitors — the laser is turned off. In larger tumors, several needles (can be) … inserted simultaneously.

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Laser Ablation of Liver Metastases from Colorectal Cancer with MR Thermometry: 5-Year Survival

Purpose

To determine technical success, technique effectiveness, complications, and survival after laser ablation of liver metastases from colorectal cancer.

Materials and Methods

Eighty-seven consecutive patients (65 men and 22 women; mean age, 62.8 years) with 180 liver metastases from colorectal carcinoma were included between 1998 and 2005. They underwent laser ablation with magnetic resonance (MR) thermometry in 170 sessions. Indications for laser ablation were locally unresectable tumors (16.1%), metastases in both liver lobes (34.5%), and refusal of surgery and/or general contraindications to surgery (49.4%). Technical success, technique effectiveness, and complication and survival rates were evaluated retrospectively.

Results

Technical success was achieved in 178 of 180 sessions (99%). Follow-up after 24–48 hours demonstrated an effectiveness rate of 85.6%. Local tumor progression rate was 10% after 6 months. Major complications included large pleural effusion, large subcapsular hematoma, abscess, large pneumothorax, pleuritis with fever, intrahepatic hemorrhage, and biloma. Mean survival from the time of diagnosis of the primary tumor was 50.6 months for all patients treated (95% CI, 44.9–56.3 months). Median survival time was 54 months and survival rates were 95.7% at 1 year, 86.2% at 2 years, 72.4% at 3 years, 50.1% at 4 years, and 33.4% at 5 years. The mean survival time after the first treatment was 31.1 months (95% CI, 26.9–35.3 months).

Conclusions

Laser ablation of liver metastases of colorectal cancer with MR thermometry appears safe and efficacious. Although the results are encouraging, direct comparison with other ablative modalities in a prospective clinical trial would be necessary to definitely show one modality is superior.

Source:
Journal of Vascular and Interventional Radiology, Volume 20, Issue 2, Pages 225-234 (February 2009)

Liver tumours and MR-guided laser ablation

20 December 2005
www.mtbeurope.info

Destruction of cancerous liver tissue by laser light guided by magnetic resonance (MR) imaging was found to be as effective as traditional surgery for some patients, in a large-scale, 12-year study in Germany.

In the largest study of its type with the longest follow-up, 839 patients at the University of Frankfurt in Germany received MR-guided laser-induced thermotherapy (LITT) for the treatment of liver tumours resulting from colorectal cancer. Between 1993 and 2005, the researchers treated 2,506 liver tumours and tracked survival rates to evaluate the long-term results of the procedure. The average survival rate from the date of diagnosis was 3.8 years, which compares favourably to survival rates after traditional surgery (approximately 1.5 to 5.0 years). The study was presented at the annual meeting of the Radiological Society of North America (RSNA).

In LITT, also known as laser ablation, laser light is used to destroy tumour tissue. According to the study’s lead author, Martin Mack, M.D., laser ablation has many advantages over other treatment methods.

“Traditional surgical resection has higher morbidity and mortality rates than laser ablation,” said Dr. Mack, an associate professor in the department of diagnostic and interventional radiology at the University of Frankfurt. “Laser treatment can be done on an outpatient basis under local anaesthesia. Typically, the patient stays only a couple of hours, instead of a couple of weeks in the hospital after surgical liver resection,” he said.

Laser ablation can be used to on tumours that occur in both halves of the liver — often during the same treatment — which is practically impossible in a traditional surgery where typically only the left or right lobe is resected. If new tumours are found during follow-up exams, it is much easier to repeat laser ablation than to subject the patient to another open surgery.

Laser ablation also holds advantages over radiofrequency ablation, another minimally invasive method of treating liver tumours, because it can be applied to different parts of the liver simultaneously and can be used with MR guidance to provide the radiologist with an accurate image of the tumour for precise targeting throughout the procedure. Radiofrequency ablation can only treat one tumour at a time and cannot be used with continuous MR monitoring.

Dr. Mack believes that laser combined with MR guidance will have wide-ranging impact on the treatment of tumours throughout the body, and may one day replace traditional surgery as the gold standard of treatment.

“Many surgeons are already performing local ablation instead of resection, because they have already recognized the positive effect of local ablation,” he said. “I believe that minimally invasive tumour ablation together with chemotherapy will play the most important role in the treatment of tumours in the years to come.”