Natural Human Immune Response Damages DNA And Is Cancer Causing: Over Two-Thirds Of DNA Damage In Some Cancers (Bladder, Cervical, Breast, Head and Neck, and Lung) Caused By Natural Immune Response

From The National Institutes of Health, "NIH scientists find that proteins involved in immunity potentially cause cancer:"

A set of proteins involved in the body’s natural defenses produces a large number of mutations in human DNA, according to a study led by researchers at the National Institutes of Health. The findings suggest that these naturally produced mutations are just as powerful as known cancer-causing agents in producing tumors.

The proteins are part of a group called apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) cytidine deaminases. The investigators found that APOBEC mutations can outnumber all other mutations in some cancers, accounting for over two-thirds in some bladder, cervical, breast, head and neck, and lung tumors.