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How can radiation exposure increase the risk of leukemia?

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Illustration of a blood vessel with a cutaway view showing red blood cells, white blood cells, platelets, and plasma, each labeled to highlight the main components of blood. — white blood cell Blood is made up of multiple components, including red blood cells, white blood cells, platelets, and water-rich plasma.

Ionizing radiation increases the risk of leukemia primarily by damaging the DNA within the blood-forming cells of the bone marrow.12

These bone marrow cells are among the most radiosensitive in the body. When exposed to ionizing radiation, the energy can cause multiple, closely spaced lesions in the DNA that overwhelm the cell's DNA repair mechanisms. While many damaged cells are eliminated by the body's natural response pathways, some may escape these defenses, propagate, and undergo malignant transformation, which is a critical step in the development of cancer.21

Leukemia was the first human cancer for which this dose-dependent risk was unequivocally demonstrated, notably among atomic bomb survivors and patients treated with X-rays for medical conditions. The incidence of most forms of leukemia (excluding chronic lymphatic leukemia) has been observed to increase roughly in proportion to the radiation dose received by the bone marrow.34