Oral Mucositis (OM) is a frequent complication of head and neck cancer (HNC) treatment with radiotherapy (RT) or chemotherapy (CT), whether individualized or combined [1]. OM is characterized by erythema and painful ulcerations that impair patients’ speech and feeding, compromising their quality of life [2]. In severe cases, OM is associated with the need for enteral or parenteral nutrition, hospitalization, an increase in treatment costs, and the interruption of cancer therapy [[3], [4]]. Discontinuing treatment before completion of the planned regimen may cause a negative impact upon the prognosis, in turn favoring local and distant recurrences [5].

OM is a consequence from direct tissue damage by RT and CT. Nonetheless, microorganisms can worsen OM lesions by exacerbating inflammation through enzymatic mucosal destruction and the control of the production and release of pro-inflammatory cytokines [[6], [7]].

Photobiomodulation (PBM-T) is a consolidated treatment for OM and is recommended by the Mucositis Study Group of the Multinational Association of Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO) to both prevent and treat OM in head and neck cancer patients [1,8]. PBM-T produces analgesic and tissue biostimulation effects, [1,8] while improving oxygenation, favoring the reestablishment of microcirculation, diminishing the edema, increasing the expression of growth factors, and promoting wound healing [[9], [10], [11]].

We hypothesized that the association of PDT with PBM-T could improve the results of PBM-T in the treatment of OM, since OM is worsened when contaminated by microorganisms [[6], [7]]. It is important to note that no previous quality controlled study has specifically evaluated the effect of PDT for OM treatment, as compared to supportive care, in oral and oropharyngeal cancer patients.

PDT treatment involves the combination of a photosensitizing agent followed by exposure to visible non-thermal light. Finsen, Raab, and Von Tapeiner were the early pioneers in the search for phototherapy, even though light has been employed in the treatment of diseases since antiquity [12,13]. Microorganisms can be sensitized to light through prior treatment with a chemical photosensitizing agent. The energy transferred from the irradiated PS generates reactive oxygen species that induce the death of microorganisms, thereby enhancing the disinfection processes [9]. Wilson [14,13] also described the advantages of this approach, including a useful alternative to antibiotics in oral infections.

The present study aimed to compare the PBM-T alone and the PBM-T associated with PDT in the wound healing process of OM in patients undergoing CT-RT for oral and oropharyngeal cancer, considering the parameters of size, duration, pain due to lesions, and microbiological analysis. The results of this study will be important to provide new insights on possible therapies for OM.