The above results suggested that the anti-tumor immunity generated by radiotherapy alone or the combination of radiotherapy and STING agonists depended on the regulation of CD8+ T cells activation and differentiation by the cGAS-STING signal pathway, which also provided a direction for the combined use of the cGAS-STING signal pathway agonists and radiotherapy for tumor treatment. The gene discussed is CD8A; the disease is neoplasm.