Low-dose Total Body Irradiation Can Enhance Systemic Immune Related Response Induced By Hypo-fractionated Radiation

objective: A systemic immune related response(SIME)of radiotherapy has been occasionally observed on metastatic tumors,but the clinical outcomes remain poor.Novel treatment approaches are therefore needed to improve SIME ratio.Methods: We used a combination of hypo-fractionated radiation therapy(H-RT)with low-dose total body irradiation(L-TBI)in a syngeneic mouse model of breast and colon carcinoma.Results: The combination therapy of H-RT and L-TBI potentially enhanced SIME by infiltration of CD8+ T cell and altering the immunosuppressive microenvironment in non-irradiated subcutaneous tumor lesions.The frequency of IFN-?,as a tumor-specific CD8+ T cells producing,significantly inhibited the secondary tumor growth of breast and colon.Conclusion:Our findings suggest that L-TBI could serve as a potential therapeutic agent for metastatic breast and colon cancer and,together with H-RT,their therapeutic potential is enhanced significantly.