Cancer’s ability to elude the immune system is a well-known characteristic. While much research has focused on somatic mutations within cancer cells that enable this evasion, little attention has been given to somatic mutations in tumor-infiltrating immune (TII) cells. These mutations do not directly fuel tumor growth but may indirectly support it by hindering an effective anti-tumor immune response. In essence, investigating these mutations in TII cells could provide valuable insights into how cancers manage to evade our immune defenses.