# What is radiation therapy? Radiation therapy, also known as radiotherapy, is a type of cancer treatment that uses high-energy beams, such as X-rays or protons, to kill cancer cells or shrink tumours. During radiation therapy, a machine called a linear accelerator is used to deliver the high-energy beams to the area of the body where the cancer is located. The beams pass through the skin and other tissues to reach the cancer cells. The energy from the beams damages the DNA of the cancer cells, which can prevent them from dividing and growing. Radiation therapy can be used to treat many types of cancer, including breast cancer, prostate cancer, colorectal and lung cancer. It is often used in combination with other treatments, such as [chemotherapy](Chemotherapy.md) or [surgery](Surgery.md). Radiation therapy can be administered in different ways, depending on the location and stage of the cancer: 1. External beam radiation: This is the most common type of radiation therapy. It involves using a machine to deliver the radiation from outside the body. 2. Internal radiation: Also known as brachytherapy, this type of radiation therapy involves placing a small, radioactive source inside the body, near the cancer cells. 3. Systemic radiation: This type of radiation therapy involves taking a radioactive substance by mouth or injection, which then travels throughout the body to kill cancer cells. Radiation therapy can have many side effects, such as fatigue, skin irritation, and nausea. These side effects are usually temporary and can be managed with medications. ## Radiation therapy & supplements My radiation oncologist [Dr. Mitchell Lui](../../../3-Resources/Cancer%20Notes/My%20Doctors/Dr.%20Mitchell%20Lui.md) said he had no issues or concerns with what I was eating or taking. There is some older research (possibly flawed by the sounds of today's assessments of it) that concluded antioxidants can interfere with some cancer treatments such as radiotherapy. But digging into some more resent research studies on the topic, it seems there is little reason to be concerned, and actually more current research findings (see below) indicate antioxidants are beneficial to these treatments: >With few exceptions, most of the studies draw positive conclusions about the interaction of antioxidants and radiotherapy. Although further studies are needed, the preponderance of evidence supports a provisional conclusion that dietary antioxidants do not conflict with the use of radiotherapy in the treatment of a wide variety of cancers and may significantly mitigate the adverse effects of that treatment. >Source: [Do antioxidants interfere with radiation therapy for cancer? - PubMed](https://pubmed.ncbi.nlm.nih.gov/17761641/) >**Conclusions:** Since the 1970s, 280 peer-reviewed in vitro and in vivo studies, including 50 human studies involving 8,521 patients, 5,081 of whom were given nutrients, have consistently shown that non-prescription antioxidants and other nutrients do not interfere with therapeutic modalities for cancer. Furthermore, they enhance the killing of therapeutic modalities for cancer, decrease their side effects, and protect normal tissue. In 15 human studies, 3,738 patients who took non-prescription antioxidants and other nutrients actually had increased survival. >Source: [Antioxidants and other nutrients do not interfere with chemotherapy or radiation therapy and can increase kill and increase survival, part 1 - PubMed](https://pubmed.ncbi.nlm.nih.gov/17283738/) >"Our study suggests supplements containing self-care dosages of vitamins, minerals, and antioxidants can be taken safely by prostate cancer patients during radiotherapy. However, longer follow-up in a larger patient population is needed to confirm these initial findings." >Source: [Antioxidant use appears safe during radiation therapy for prostate cancer](https://www.urologytimes.com/view/antioxidant-use-appears-safe-during-radiation-therapy-prostate-cancer)