IFNA1 and cancer: We first summarize the immune response to viruses, discussing the activation of innate immune receptors that ultimately promotes IFN responses and activation of adaptive immunity; we next discuss the clinical meaning of interferon activation in tumors and the impact of cancer-associated viruses and EREs in the tumor immune microenvironment; finally, we present therapeutic approaches employing this knowledge to boost antitumor immune responses that are currently under development and clinical testing.