A single application of low-level light therapy in breast cancer-bearing mice

Abstract

Low-level light therapy (LLLT) has been used in healthcare as a therapeutic strategy for diseases of various aetiologies. However, its effects on cancer is controversial. The aim of this work was to evaluate the effects of different light doses on blood cell count of breast cancer-bearing mice after a single application of LLLT. Tumour was induced by inoculation of 4T1 cells into the mammary fat pad of female BALB/c mice. Tumour volume was monitored with a digital calliper and when it reached 100 mm3, animals were irradiated by a red LED irradiator (660 ± 20 nm) at irradiance of 24.3 mW/cm2. The animals were randomly divided into groups (n= 5/group) that received energy densities of 1.8, 5.6 and 9.4 J/cm2. Control group was equally manipulated but did not receive irradiation. After treatment, data as tumour volume, platelets, white and red cell levels were registered weekly during 21 days. Our results showed that irradiated groups presented a longer survival compared to the control group, although no significant differences were observed among groups regarding tumour volume. Platelet levels of the irradiated groups remained closer to the reference values of healthy animals. Regarding the total number of white and red cells, no significant differences were observed between control and treated groups. These findings indicate that LLLT in a single application did not arrest tumour growth but may maintain platelet levels to increase survival of mice regardless the energy density protocol used.