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Low-level laser evidence inclonclusive; results mixed

Dr. Alam
Dallas — Patients' interest in minimally invasive treatments could bode well for the future of low-level laser therapy (LLLT) in the United States, but only if its efficacy can be proven. "Everyone is looking for some way to make their scars less visible," says Murad Alam, M.D., chief, section of cutaneous and aesthetic surgery, department of dermatology, Northwestern University. "Patients are always delighted to use vitamin A, or whatever, even if there's no evidence that it works. So patients would crave something that would have any hope of making their scars better. And they would be particularly prone to like things that wouldn't hurt and weren't necessarily invasive or high-cost." .

The above characteristics describe LLLT — which is widely used in Canada, Asia and Europe — to a T. Low-level lasers are compact, often hand-held units that operate at a power range between 10-3 to 10-1 W and at wavelengths between 300 nm and 10,600 nm. "The theory is that even low levels of light can modulate biological processes," says Dr. Alam, who presented a paper on LLLT at the recent American Society for Laser Medicine and Surgery annual meeting. To help determine if this is true, he and several colleagues examined approximately 50 studies of LLLT's role in wound healing. While literature exists, Dr. Alam says, "not everyone buys it. So it was a matter of assessing the literature critically" to see what it reveals.

Research generally falls into three categories: cellular, animal and human studies. "At the cellular level, there are a number of studies looking particularly at fibroblasts in wound healing and showing that low-level laser light might have some impact on fibroblasts," Dr. Alam says. Specifically, studies appear to show that exposure to LLLT increases collagen deposition as well as proliferation of fibroblasts and other cells. However, other studies contradict these findings

Animal results mixed Animal studies, too, reveal mixed results. While rodent models suggest LLLT improves wound closure and tensile strength, Dr. Alam says that "unfortunately, the animal studies have not been very convincing in porcine models." In humans, he adds, "there has been some evidence of success in healing of wound status after use of low-level laser light, but it's been quite equivocal. And more significantly, some of the 'gold standard' randomized controlled trials failed to show much consistent benefit, which brings us to the possible conclusion that maybe the other trials showed benefits just because the trials themselves weren't well-designed and didn't account well for their own experimental biases."

Accordingly, researchers concluded that LLLT's efficacy remains unclear. "Even the investigation of prior studies is complicated by the fact that there is no standardization among them. They've been ad hoc. They haven't really been randomized, controlled trials. Different lasers and parameters have been used. As a consequence, it's hard to come up with particular conclusions, but at best (LLLT) hasn't been demonstrated in humans to be particularly helpful," Dr. Alam says.

Nevertheless, LLLT's effectiveness hasn't been disproven, either. "It's still an interesting idea," he says. "It's low-hanging fruit." What's needed are small, dose-finding studies to address issues including which lasers work best and how often they should be used. After that, larger, controlled trials could follow. Such studies haven't been performed partly because they amount to unfunded research that currently lacks a commercial champion. Although LLLT's credibility has suffered stateside, Dr. Alam adds, the treatment could be ripe for re-evaluation.

"If it can be shown that LLLT works and makes even a modest effect .... it would probably catch on," he says.

Dr. Alam possesses no financial interests related to this article.

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