Publications & Research on Photobiomodulation

Phase III trial terminated due to futility: transcranial laser therapy showed no benefit on functional outcome at 90 days after an acute ischemic stroke. The result was negative, and the trial was terminated early.

MASCC/ISOO Clinical Practice Guidelines on Mucositis Associated with Cancer Treatment. Based on 570 selected articles, they include 32 recommendations, 22 of which address oral mucositis and 10 address gastrointestinal mucositis.

A systematic review with meta-analysis of 13 randomized trials of acceptable quality. When administered before exercise, light therapy increases the time to exhaustion by 4.12 seconds and adds 5.47 repetitions compared with placebo.

A leading narrative review on photobiomodulation in dermatology, without a meta-analysis. The authors describe effects on wrinkles, scars, and burn healing, with very few reported adverse effects.

MASCC/ISOO systematic review on laser and other light therapies for oral mucositis. It established a recommendation for the use of low-intensity laser therapy as a preventive measure in adult stem cell transplant recipients.

This 2011 review brings together the cellular and tissue mechanisms of photobiomodulation, light sources, and the principles of dosimetry. It describes a field of research without demonstrating the effectiveness of any specific protocol.

In this belated review, Tiina Karu provides an overview of the effects of red and near-infrared radiation on mammalian cells and human skin. She highlights the dual role of cytochrome c oxidase as both a photoacceptor and a signal transducer.

A meta-analysis of 16 randomized trials involving 820 patients, published in *The Lancet* in 2009. Photobiomodulation reduces the intensity of neck pain by 19.86 mm out of 100 mm, with the benefit persisting for up to 22 weeks after treatment.

A 2009 review of the biphasic dose response in photobiomodulation. It shows that, beyond a certain optimal level, increasing light intensity does not improve tissue repair, and sheds light on conflicting results.

This review describes the retrograde signaling pathway connecting the mitochondria to the nucleus when mammalian cells are exposed to red or near-infrared light. It is based on laboratory studies, not on clinical trials.

Using monolayers of HeLa cells, this laboratory study recorded the cellular absorption spectra and demonstrated that irradiation at 830 nm reduces cytochrome c oxidase. The absorption spectra coincide with the known action spectra.

In 2005, nitric oxide donors suppressed the light-induced increase in HeLa cell adhesion and shifted the spectrum of action. This was a laboratory study using cells, with no clinical trials.

A multicenter, double-blind, randomized trial involving 30 patients who underwent radiation therapy for head and neck cancer. The 632.8-nm helium-neon laser reduced the incidence of grade 3 mucositis from 35.2% to 7.6% and that of severe pain from 23.8% to 1.9%.