Which body tissue is most likely to develop cancer from equal doses of ionizing radiation?

Which body tissue is most likely to develop cancer from equal doses of ionizing radiation?

• A. Skin
• B. Breasts
• C. Brain
• D. Spleen

Answer: (B)

The tendency for radiation to cause cancer in a tissue depends on how readily its cells can accumulate unrepaired DNA damage over time. Breast tissue has many glandular epithelial cells that actively divide during puberty, pregnancy, and lactation. That ongoing cell turnover provides more targets for radiation-induced mutations, and over the long lifetime after exposure these mutations can accumulate into malignant changes. The breast therefore has a higher risk of developing cancer from a given amount of ionizing radiation compared with tissues where cells divide less or are more specialized. Brain tissue, composed mostly of mature neurons and non-dividing cells, is relatively resistant to radiation-induced cancers because there are fewer cells undergoing division to acquire and propagate mutations. The spleen contains hematopoietic cells that are radiosensitive, but cancers there are less common and the organ’s response to radiation often emphasizes acute effects rather than long-term solid tumor development. Skin can develop cancers from radiation as well, but when comparing these tissues, the breast presents the greatest likelihood of radiation-induced cancer for equal doses due to its high proliferative target cell population and long window for mutation accumulation.

The tendency for radiation to cause cancer in a tissue depends on how readily its cells can accumulate unrepaired DNA damage over time. Breast tissue has many glandular epithelial cells that actively divide during puberty, pregnancy, and lactation. That ongoing cell turnover provides more targets for radiation-induced mutations, and over the long lifetime after exposure these mutations can accumulate into malignant changes. The breast therefore has a higher risk of developing cancer from a given amount of ionizing radiation compared with tissues where cells divide less or are more specialized.

Brain tissue, composed mostly of mature neurons and non-dividing cells, is relatively resistant to radiation-induced cancers because there are fewer cells undergoing division to acquire and propagate mutations. The spleen contains hematopoietic cells that are radiosensitive, but cancers there are less common and the organ’s response to radiation often emphasizes acute effects rather than long-term solid tumor development. Skin can develop cancers from radiation as well, but when comparing these tissues, the breast presents the greatest likelihood of radiation-induced cancer for equal doses due to its high proliferative target cell population and long window for mutation accumulation.