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Purpose: There is a large body of evidence supporting the efficacy of low-level laser therapy (LLLT), more recently termed photobiomodulation (PBM) for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved and dosimetric parameters may lead to the management of a broader range of complications associated with HNC treatment. This could enhance patient adherence to cancer therapy, and improve quality of life and treatment outcomes. The mechanisms of action, dosimetric, and safety considerations for PBM have been reviewed in part 1. Part 2 discusses the head and neck treatment side effects for which PBM may prove to be effective. In addition, PBM parameters for each of these complications are suggested and future research directions are discussed.Methods: Narrative review and presentation of PBM parameters are based on current evidence and expert opinion.Results: PBM may have potential applications in the management of a broad range of side effects of (chemo)radiation therapy (CRT) in patients being treated for HNC. For OM management, optimal PBM parameters identified were as follows: wavelength, typically between 633 and 685 nm or 780-830 nm; energy density, laser or light-emitting diode (LED) output between 10 and 150 mW; dose, 2-3 J (J/cm(2)), and no more than 6 J/cm(2) on the tissue surface treated; treatment schedule, two to three times a week up to daily; emission type, pulsed (<100 Hz); and route of delivery, intraorally and/or transcutaneously. To facilitate further studies, we propose potentially effective PBM parameters for prophylactic and therapeutic use in supportive care for dermatitis, dysphagia, dry mouth, dysgeusia, trismus, necrosis, lymphedema, and voice/speech alterations.Conclusion: PBM may have a role in supportive care for a broad range of complications associated with the treatment of HNC with CRT. The suggested PBM irradiation and dosimetric parameters, which are potentially effective for these complications, are intended to provide guidance for well-designed future studies. It is imperative that such studies include elucidating the effects of PBM on oncology treatment outcomes. [ABSTRACT FROM AUTHOR]

Purpose: There is a large body of evidence supporting the efficacy of low level laser therapy (LLLT), more recently termed photobiomodulation (PBM), for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved, may expand the applications for PBM in the management of other complications associated with HNC treatment. This article (part 1) describes PBM mechanisms of action, dosimetry, and safety aspects and, in doing so, provides a basis for a companion paper (part 2) which describes the potential breadth of potential applications of PBM in the management of side-effects of (chemo)radiation therapy in patients being treated for HNC and proposes PBM parameters.Methods: This study is a narrative non-systematic review.Results: We review PBM mechanisms of action and dosimetric considerations. Virtually, all conditions modulated by PBM (e.g., ulceration, inflammation, lymphedema, pain, fibrosis, neurological and muscular injury) are thought to be involved in the pathogenesis of (chemo)radiation therapy-induced complications in patients treated for HNC. The impact of PBM on tumor behavior and tumor response to treatment has been insufficiently studied. In vitro studies assessing the effect of PBM on tumor cells report conflicting results, perhaps attributable to inconsistencies of PBM power and dose. Nonetheless, the biological bases for the broad clinical activities ascribed to PBM have also been noted to be similar to those activities and pathways associated with negative tumor behaviors and impeded response to treatment. While there are no anecdotal descriptions of poor tumor outcomes in patients treated with PBM, confirming its neutrality with respect to cancer responsiveness is a critical priority.Conclusion: Based on its therapeutic effects, PBM may have utility in a broad range of oral, oropharyngeal, facial, and neck complications of HNC treatment. Although evidence suggests that PBM using LLLT is safe in HNC patients, more research is imperative and vigilance remains warranted to detect any potential adverse effects of PBM on cancer treatment outcomes and survival. [ABSTRACT FROM AUTHOR]

Summary: Background: One of the mechanisms through which photodynamic therapy (PDT) is thought to elicit tumour destruction is by producing microvascular damage and obstruction of nutritive blood flow. The aim of this study was to directly monitor and quantify microcirculatory changes following tissue illumination by PDT for oral squamous cell carcinoma. Methods: Ten consecutive patients receiving PDT for a carcinoma in situ, a T1 or T2 tumour in the oral cavity without evidence of lymph node metastasis were selected for this study. Tumour and marginal healthy mucosa total capillary density (TCD) and functional capillary density (FCD) inside the field of illumination were measured and compared using sidestream dark-field (SDF) imaging prior to tissue illumination, immediately after PDT, and again after 15min. Results: Baseline mean tumour TCD was 21.2±5capillaries per square millimetres (cpll/mm2) and 24.9±19cpll/mm2 in the surrounding marginal healthy tissue; there were no significant differences between tumour and healthy tissue or time points. Comparisons between baseline and post-illumination time points revealed significant differences in both tumour and healthy tissue FCD (P <0.05). No significant differences in FCD were observed between the two tissues. Conclusions: Our findings using SDF imaging demonstrate that PDT significantly attenuates tumour and marginal healthy tissue perfusion by directly disrupting the functionality of the microcirculation. [Copyright &y& Elsevier]

A high incidence of oral complications is associated with chemotherapy (CT) treatment in cancer patients; however, while knowledge into molecular mechanisms of their pathobiology continue to evolve, the direct physiological effects of CT on oral tissue perfusion remain unexplored. The aim of this investigation was to assess the acute effects of CT on gingival microcirculation perfusion by measuring gingival capillary density. Twenty female specific-pathogen free New Zealand White rabbits were randomly divided into four groups receiving four different intravenous dose levels of cyclophosphamide, methotrexate, and fluorouracil (CMF). Noninvasive measurements of gingival capillary density were performed using sidestream dark-field (SDF) imaging prior to and 30 min after CT treatment. Four rabbits receiving saline solution were used as control animals. Baseline gingival capillary density was 58 ± 11 cpll/mm2, no significant differences in baseline capillary densities between the groups were found. From low to high dose CT, capillary density 30 min after CMF treatment increased in each group by 1 ± 7, 5 ± 7, 13 ± 18 and 20 ± 13 cpll/mm2, respectively. Capillary density increase was significant in the high-dose group. No change in gingival capillary density was found in the control group. Periodontal microcirculation perfusion had increased 30 min after CT treatment as indicated by a rise in gingival capillary density. Our results support the idea that CT-induced microcirculatory response not only diligently delivers but also saturates peripheral oral tissues with antineoplastic agents by increasing surface area exposure. This functional response of the microcirculation to CT drugs may play a role in contribution to oral complications and the treatment of oral tumors. [ABSTRACT FROM AUTHOR]