INTERSTITIAL LASER THERAPY/NEUROLOGY/ONCOLOGY: ASLMS conference highlights applications of interstitial laser therapy, laser-assisted stem cell therapy

During the 31st Annual Conference of the American Society for Laser Medicine and Surgery (ASLMS, March 30–April 3, 2011, Grapevine, TX), Jill Waibel presented a porcine study showing that fractional laser devices appear to have potential for delivering intact and functional stem cells into the skin. If replicated in humans, laser-assisted stem cell transplants could help patients generate their own new skin, immediately following a traumatic event. Though the studies are still in their infancy, such therapy could be a tremendous help to patients with burns on more than 50 percent of their bodies, since they don’t often have enough skin to do grafts.

Also at the event, an “Interstitial Laser Therapy and Surgery” session presented promising research data regarding the treatment of benign prostatic hyperplasia (BPH) and cancers of the brain, prostate, liver, pancreas, kidney and breast. The precise heat delivery enabled by interstitial laser therapy (ILT) could ablate a tumor, while still preserving sexual function and bladder control in patients, for instance.1 It could also selectively target areas in the brain, helping patients who suffer severe and continuous epileptic seizures. In fact, a pilot study, backed by a New Therapy Grant from the Epilepsy Foundation, is helping Visualase Inc. (Houston, TX) to determine the feasibility of MRI-guided laser ablation of epileptogenic seizure foci. For many epileptic patients, surgical resection offers a potentially curative therapy, yet few elect to undergo resection. The foundation hypothesizes that “precise destruction of epileptogenic foci using a minimally invasive technique known as laser induced thermal therapy (LITT) would provide results approaching surgical resection in terms of seizure relief, and could be carried out with a far lower risk of surgical morbidity to the patient.”

ILT offers advantages over other minimally invasive methods such as microwave technology, radiofrequency and cryotherapy. For instance, radiofrequency probes get very hot right at the tip, and it takes a while for that heat to distribute throughout the tissue, said Roger McNichols, chief technology officer at Visualase. The more it distributes, the larger the thermal lesion. With laser, there is rapid volumetric heating around the applicator, which leads to steeper thermal gradients and sharper demarcation of thermal lesion borders. Further, heating with ILT can be observed with real-time magnetic resonance imaging (MRI) during the treatment, whereas other ablation methods can interfere with MRI. Thus, surgeons can use MRI to guide the laser ablation, opening doors to new areas of treatment, specifically in the brain. What’s more, ILT can be adjusted through the use of different wavelengths.

ILT may also have cancer-fighting effects beyond tumor and tissue ablation. In fact, ILT administered at specific temperatures seems to elicit an immune response that can independently fight other non-treated tumors, said Karl G. Tranberg, professor of surgery at Lund University in Sweden. “When administered at a range of 46° to 48°C for about a half-hour, ILT can ablate the tumor, and the slow cell death gives release of non-coagulated proteins and tumor antigens,” he explained. “Preserved tumor antigens are exposed to the immune system, which induces anti-tumor immunity in the host.”

The idea of a laser-mediated immunologic effect is based on a clinical observation. Tranberg noted that the extent of the effect on tumor after endoscopic laser treatment of colorectal cancer was far larger than the size of the initial destruction. This observation prompted a series of studies using a chemically induced colonic adenocarcinoma implanted into the livers of rats. After he used ILT, Tranberg implanted a second tumor in the rat. The body completely eradicated the untreated tumor and showed no signs of metastasis. In addition, the number of ED1 macrophages and CD8 lymphocytes, which are measures of immune response, was higher in rats treated with ILT. Even more convincing, treatment of one tumor eradicated another simultaneously implanted and untreated tumor at a distant site. Dr. Tranberg also replicated this latter finding in one patient with malignant melanoma, who had distant tumor resolution after ILT as well.

The technology holds tremendous promise, though applications are only just beginning to be discovered, said Tranberg. “ILT gives precise control of the lesion size and has a low risk of complications,” he added. “The minimally invasive nature of the treatment guarantees a relatively small trauma and a good aesthetic outcome.” —Barbara G. Goode

1. O. Raz et al., European Urology 58 (1), e1–e18 (2010).

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