Efeito da fototerapia de baixa intensidade associado à radioterapia no carcinoma de células escamosas bucal e aplicação da fotobiomodulação na radiossensitividade de células cancerígenas

Abstract

Oral squamous cell carcinoma (OSCC) is the most common type of oral malignancy (90%), being the main cause of morbidity and mortality in patients with head and neck cancer. Radiation therapy is currently the standard adjuvant treatment; however, it is accompanied by several complications resulting from damage to radiosensitive tissues located close to the tumor. Therefore, PBM has attracted attention in various clinical fields with a new generation of LEDs for the repair of injured tissues. Thus, the present study aimed to investigate the cellularresponse of oral squamous cell carcinoma with pre-exposure to low-level phototherapy before radiotherapy, in addition to a literature review that evaluated data that investigated the application of PBM as a radiosensitizer of cancer cells. For the experimental study, cell lines SCC9, Cal-27, A431 and HaCaT were submitted to low-level phototherapy and radiotherapy. Cells were treated with a single energy density (300 J/cm2 ) of a light emitting diode (660 nm) before ionizing radiation at different doses (0, 2, 4 and 6 Gy). After 24 h, analyzes of migration, proliferation, clonogenic assay, cell death and reactive oxygen species (ROS) were performed to assess the cellular response. In the review study, a search was carried out in the MEDLINE/PubMed and academic google databases, using the terms “PBM, low level light therapy, cell cancer, cell tumors, radiosentitizer, and ionizing radiation”. The experimental results showed that the cell lines pre-exposed to PBM at the analyzed dosage were radiosensitive. The treatment significantly reduced cell proliferation and survival of clonogenic cells. The migration and cell death assays also revealed positive results, with the treatment group having a lower migration rate and greater cell death than the control group. Furthermore,PBM effectively increased intracellular levels of ROS. Thus, it is concluded with the experimental study that phototherapy at 300 J/cm2 is a promising radiosensitizing modality to reduce the radiation dose and avoid the intolerable side effects of radiotherapy for head and neck CCEB, thus increasing the probability of treatment success. The results obtained with thereview showed that only five studies evaluated PBM as a possible radiosensitizing agent for cancer cells, and in these studies the cell lines HeLa, HeLa Kyoto and A431 were evaluated, and in almost all studies, pre-exposure of PBM led to a positive effect in fighting the cells. Therefore, further studies should be carried out to evaluate PBM as a technique that improves the results of cancer treatments, increasing tumor eradication and reducing the adverse effects of radiation.