Moreover, our findings reveal a pivotal, senescence‐associated cross talk between IR‐induced cytokines/chemokines, IL‐6, IL‐1, and CCL20, produced by keratinocytes and fibroblasts, and chemokine‐mediated infiltration of IL‐17‐producing Ccr6+ T cells that, in an apparent feedback loop, drive the hallmark features of radiodermatitis and transient hair loss (Appendix Fig S16). The gene discussed is CCR6; the disease is radiodermatitis.