preliminary results of the effects of localized high-dose radiotherapy combined with total body low-dose irradiation on tumor growth and stimulating the immune system in tumor-bearing mice

Background: the immune system plays an extensive role in eliminating tumor cells. on the other hand, low-dose irradiation stimulates the immune system.objective: the present study aimed to investigate the therapeutic outcomes of localized high-dose radiotherapy (lh) alone and combined with total body low-dose irradiation (tb).material and methods: in this experimental study, b16f0 tumor cells were injected into the right flank of c57jl/6 mice. the mice were treated with lh alone (13 gy x-rays to the tumor surface) (lh group) or combined with tb (85 mgy x-rays at the skin) (tb+lh group). then the tumor volume, the mice’s lifespan, the number of lymphocytes extracted from the spleen, and interferon gamma (ifn-γ) production were measured.results: reduced number of lymphocytes, compared to non-irradiated mice (control group), was observed in lh and tb+lh groups. however, the identical number of cultured lymphocytes produced a higher level of ifn-γ in irradiated groups. comparing the irradiated groups, the number of lymphocytes and their ifn-γ production, tumor growth control, and the mice’s lifespan were statistically higher in tb+lh group. conclusion: observing a higher level of ifn-γ in tb+lh group compared to lh group indicates that low-dose radiation enhanced the stimulating effects of high-dose radiation on the immune system. it caused the mice in tb+lh group to have a more prolonged lifespan and a lower tumor growth rate. therefore, it is worth our attention for future studies to investigate whether total body low-dose irradiation can be utilized before radiotherapy to enhance its efficiency.