Photobiomodulation enhances radiosensitivity and suppresses oral squamous cell carcinoma in a 4NQO-induced mouse model.

This study aims to investigate the effects of photobiomodulation (PBM) on the treatment of head and neck squamous cell carcinoma (HNSCC) with Radiation Therapy (RT). An experimental in vivo study was conducted using a 4-nitroquinoline-1-oxide (4NQO)-induced oral carcinogenesis model in Swiss mice (n = 50), which were randomly divided into four groups. The control group (n = 5) received no treatment, while all other groups (n = 15 each) were exposed to 4NQO via drinking water. One group received only 4NQO, another received 4NQO followed by localized radiotherapy (16 Gy) to the oral region, and the final group received photobiomodulation before radiotherapy using a 660 nm laser (9 J, 300 J/cm²). Histological and immunohistochemical analyses (VEGF, Bax) were performed to assess tissue response and molecular changes. Ethical approval: nº001/2023. PBM associated with radiotherapy appears to have a potential radiosensitizing effect, as the results showed a decrease in the incidence of oral squamous cell carcinoma in the group in which PBM was applied prior to irradiation. The animals that did not receive PBM had a 9-fold risk of developing cancer compared to those treated with PBM before radiotherapy. VEGF expression was significantly reduced in all groups treated with 4NQO, regardless of whether radiotherapy or PBM was applied, compared to the control group. On the other hand, BAX expression increased significantly in the group subjected to the combination of PBM and radiotherapy, indicating a possible pro-apoptotic effect of PBM when associated with radiation. PBM shows potential as an effective pre-radiotherapy intervention, contributing to the prevention of HNSCC and modulation of tumor-related molecular pathways.