Which cancer type has the shortest latency period after radiation exposure?

• A. Lung cancer
• B. Bone cancer
• C. Leukemia
• D. Breast cancer

Answer: (C)

Latency after radiation exposure varies by tissue, and the blood-forming tissues in bone marrow are extremely radiosensitive and divide rapidly. This makes leukemia the earliest possible radiation-induced cancer, because radiation can provoke changes in hematopoietic cells that lead to clonal expansion relatively quickly. As a result, leukemia tends to appear sooner after exposure than solid tumors, which require more time for multiple mutations to accumulate in slower-growing tissues. In populations exposed to ionizing radiation, leukemia often develops within a few years—typically around 2 to 7 years after exposure—whereas solid tumors such as those in the breast, lung, or bone usually take 10 years or more, often several decades, to become clinically detectable. Dose and age at exposure can influence the exact timing, but the pattern remains that leukemia has the shortest latency among radiation-associated cancers.