Ionizing radiation (delivered via radioactive decay to target tissue)

"Ionizing radiation delivery to target tissue via radioactive decay" is not a molecular therapeutic target but rather a **therapeutic modality**. It refers broadly to the use of ionizing radiation—produced by the decay of radioactive isotopes—to destroy or shrink tumors by causing irreparable DNA damage in targeted cells. This approach includes several clinical techniques: *External beam radiation therapy* delivers focused beams from outside the body; *brachytherapy* places sealed sources near or within tumors; and *systemic radionuclide therapies* deliver radioisotopes that localize preferentially in certain tissues or are conjugated with targeting molecules such as antibodies for selective uptake by tumor cells. Examples include iodine‑131 for thyroid cancer and lutetium‑177–labeled peptides for neuroendocrine tumors. Ionizing radiation is not a receptor, enzyme, transporter, or protein but an energy form that interacts with biological molecules primarily through direct and indirect induction of double-strand breaks in DNA. While highly effective against many cancers, its use is limited by potential collateral damage to normal tissues and long-term risks including secondary cancers.

Other names

Radiation therapyRadiotherapyRadionuclide therapyRadioisotope therapyMolecular radiotherapy

Induction of DNA damage in target cells via ionization, leading to cell death/apoptosis