EGFR and cancer: Radioresistant cell types. The density of cancer stem cells (CSCs) (CD133) 51, CSCs-mediated repopulation with increased epidermal growth factor receptor (EGFR) expression 52, the postradiotherapy cancer stemness 53, cancer-associated fibroblast heterogeneity 49, 50, and myeloid-derived suppressor cells and neutrophils are risk factors for radioresistance 54.