As abundant stromal cells in the TME, cancer-associated fibroblasts (CAFs) protect cancer cells from radiation-induced death and increase cancer cell radioresistance via paracrine action by cytokines, such as CXCL1, CXCL12, IGF1/2, and PDGF, eventually leading to RT failure and cancer progression (5, 7–9). Here, CXCL12 is linked to cancer.