How do radiation treatments primarily target cancer cells?

The primary mechanism by which radiation treatments target cancer cells is through the destruction of their DNA. Cancer cells typically divide and proliferate more rapidly than normal cells. When radiation is applied, it generates harmful ionizing radiation that interacts with the molecules within the cancer cells. This interaction causes breaks in the DNA strands, leading to either direct damage or inducing reactive oxygen species that further harm the DNA.

When the DNA is severely damaged, the cancer cells lose their ability to divide and grow, ultimately leading to cell death. Normal cells can often repair themselves from radiation-induced DNA damage to a certain extent. However, the high rate of division in cancer cells makes them particularly vulnerable to radiation because they are less capable of repairing the DNA damage before they attempt another round of division.

Other approaches listed, such as enhancing blood circulation or stimulating immune cells, do not effectively describe the direct mechanism of action of radiation therapy. Similarly, slowing down cell metabolism is not a primary function of radiation treatment in the context of targeting cancer cells specifically. Thus, the destruction of DNA in cancer cells is the most accurate representation of how radiation therapy operates.