Radiation therapy exerts its effects by producing free radicals within cells, which then cause DNA damage. This damage can be in the form of single-strand breaks, double-strand breaks, or cross-linking between DNA strands. The most lethal form of damage is the double-strand break, which is difficult for cells to repair. Healthy cells have robust mechanisms to repair DNA damage, whereas cancer cells often have defective repair pathways, making them more susceptible to radiation.
