IGF-2 (insulin-like growth factor 2) promotes cancer stem cell self-renewal and drug resistance through a positive feedback loop of PI3K signaling, while IGF-1R (Insulin-like growth factor-1 receptor) signaling upregulation results in resistance to radiotherapy, and targeted inhibition of this pathway synergistically improves radiotherapy sensitivity and inhibits tumor recurrence. This evidence concerns the gene IGF2 and cancer.