Accumulating evidence indicates that radiotherapy treatment induces not only systemic anti-tumor immunity [42, 43] by increasing NK and CD8+ CTL infiltration and reducing the level of invasive regulatory T cells (Treg) [44], but also tumor recurrence and metastasis, by “awakening” cancer stem cells or improving myeloid cells recruitment [45–47]. The gene discussed is CD8A; the disease is neoplasm.