Radiation showers break the genome and cause a lot of damage simultaneously. This seems to overwhelm the DNA repair mechanism in the cell, leading to the damage we see in the DNA. Ionizing radiation, such as gamma rays, x-rays, and radioactive particles, can cause cancer by damaging DNA. However, it is not known how this occurs or how many tumors are caused by radiation damage.
It is well established that DNA damage is the primary mechanism associated with the tumorigenicity of ionizing radiation; however, ionizing radiation also causes significant aberrations in the cellular epigenome, including alterations in DNA methylation, histone modifications, and chromatin accessibility.