The DNA damage is mostly repaired by the repair mechanisms present in cells. If DNA damage is not repaired, it can cause a random change in the genetic material of the organism. These changes in the DNA are permanent and are called mutations. Mutations may be adaptive or harmful. Mutations in a protooncogene leading to overproduction of protein to allow uncontrolled cell division can cause cancer. Similarly, a loss of function in tumor suppressor genes also causes cancer.
