Strahlentherapie, or radiation therapy, is a medical treatment that uses high doses of radiation to kill cancer cells or shrink tumors. It works by damaging the DNA of the cancer cells, preventing them from growing and dividing. This therapy can be delivered externally, using a machine that directs radiation beams at the tumor, or internally, by placing radioactive material near the cancer site. Radiation therapy is often used in combination with other treatments, such as Chemotherapie or Chirurgie, to improve outcomes for patients. It can be effective for various types of cancer, including Brustkrebs and Lungenkrebs, and is typically tailored to each patient's specific needs.