Influência da fotobiomodulação em lesões induzidas por aplicação tópica de 4-nitroquinolina-n-óxido em língua de camundongos swiss

Abstract

Oral cancer has a high incidence, with squamous cell carcinoma (SCC) being the most common type. Photobiomodulation (PBM) is recognized for its anti-inflammatory and tissue repair effects, but its influence on malignant lesions remains controversial. This study evaluated the impact of PBM with red and infrared lasers in an oral carcinogenesis model induced by 4-nitroquinoline 1-oxide (4-NQO). For this purpose, 60 Swiss mice were subjected to topical application of 1% 4-NQO on the dorsal surface of the tongue daily for 20 weeks. In the negative control group (NCG), only propylene glycol and dimethyl sulfoxide (DMSO) were used, while a positive control group (PCG) received 1% 4-NQO, and four experimental groups (TG) were treated with 4-NQO and irradiated three times a week with PBM [red laser (RL) and infrared laser (IRL)]. In TG1, RL was used, and in TG2, IRL, both groups starting in the last 6 weeks of 4-NQO application. In TG3, RL was applied, and in TG4, IRL, when lesions became clinically visible in the form of erythema, white plaques, ulcers, or elevations, continuing until lesion regression or until the animal showed visible signs of distress. Animals from the PCG, NCG, TG1, and TG2 groups were euthanized in the 20th week, while TG3 and TG4 animals were euthanized in the 22nd week. The tongues were surgically removed and processed for histological analysis of cellular and architectural alterations. Body weight data were expressed as mean ± standard error of the mean (SEM) and analyzed using two-way ANOVA with Bonferroni post-test, while histopathological findings were assessed using Pearson’s chi-square test. From the 17th week onwards, the groups subjected to PBM showed a significant reduction in body mass compared to the controls (p < 0.001). Histologically, all 4-NQO-irradiated groups exhibited epithelial alterations ranging from mild dysplasia to squamous cell carcinoma, with no statistical differences among the irradiated groups (p = 0.106). It was concluded that, under the evaluated conditions, PBM demonstrated limited oncological safety, with no significant impact on tumor progression or clinically visible lesions, highlighting the need for further studies to elucidate its safety in oral carcinogenesis contexts.