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How can radiation damage chromosomes and increase cancer risk?

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BRCA2 tumor suppressor gene on chromosome 13 — human genetic disease Photomicrograph of the *BRCA2* tumor suppressor gene on chromosome 13 of the human genome. Inactivation of this growth-regulating gene is associated with a higher risk of developing breast cancer.

Radiation damages chromosomes and increases cancer risk primarily by disrupting the integrity of the DNA molecule. Ionizing radiation can cause direct damage, such as double-strand breaks in the DNA, which may lead to the loss of genetic material or the rearrangement of chromosome segments through processes like translocation.12

When these chromosomal breaks occur, they can interfere with normal cell division or result in permanent, fixed mutations if the cell's DNA repair mechanisms are slow, error-prone, or overwhelmed. These mutations can deregulate normal cell growth by altering oncogenes or tumor suppressor genes. For instance, chromosomal rearrangements can create dominant oncogenes, such as the Philadelphia chromosome associated with chronic myelogenous leukemia.134

Additionally, ionizing radiation can generate reactive forms of oxygen (free radicals) that oxidize DNA bases, further contributing to the accumulation of mutations. Because cancer is a disease of successive mutations, these radiation-induced genetic alterations can eventually lead to the uncontrolled cell proliferation characteristic of malignant tumors.324