How does the body repair damaged DNA?

The cell has multiple DNA repair pathways because DNA faces constant damage from copying mistakes, radiation, and chemicals. Proofreading during replication fixes many errors immediately, and other systems such as mismatch repair, base excision repair, and nucleotide excision repair correct different kinds of damage. More serious double-strand breaks can be repaired by mechanisms such as nonhomologous end joining or homologous recombination. These repair systems are essential for preventing mutations, cancer, and cell death.