EVALUATION OF LOW-POWER INFRARED LASER AND RED LED EFFECTS ON CELL VIABILITY AND REACTIVE OXYGEN SPECIES LEVELS IN HUMAN BREAST CANCER CELLS

Low-power lasers and LEDs, typically within the red and near-infrared spectra, are used to modulate molecular, cellular, and systemic processes based on photobiomodulation (PBM) effect. In the oncological context, this therapy is a subject of debate due to concerns that the PBM might stimulate tumor cell proliferation. This study aimed to evaluate the effects of a low-power infrared laser and red LED, applied either individually or in combination, on cell viability and reactive oxygen species (ROS) levels in human breast cancer cells. MDA-MB-231 and MCF-7 cells were exposed to infrared laser (808 nm; 1.5, 3.0, and 6.0 J; 16.6, 33.3, and 66.6 J/cm²; 200 mW; 2.2 W/cm²; 15, 30, and 60 s) and to red LED (630 nm; 1.4, 3.0, and 6.0 J; 5.6, 12, and 24 J/cm²; 320 mW; 0.16 W/cm²; 9, 19, and 38 s). Cell viability was assessed at 24, 48, and 72 hours post-exposure, while ROS levels were measured 10 minutes post-exposure. Under the conditions evaluated, exposure to laser and LED did not significantly alter cell viability but did significantly reduce ROS levels in both MDA-MB231 and MCF-7 cell cultures. The results suggest that PBM induced by infrared laser and red LED reduces oxidative stress without promoting increased viability in human breast tumor cell cultures. This work was supported by Biophotonics Laboratory of the State University of Rio de Janeiro (UERJ) and the Rio de Janeiro State Research Foundation (FAPERJ).