Radiation therapy is a type of cancer treatment that uses high doses of radiation to shrink tumors and kill cancer cells in the body. Radiation at high doses damages the DNA of cancer cells to stop them from dividing. When at low doses, it is used in x-rays to see inside the body as with x-rays of broken bones or checking your teeth. Radiation is administered to a patient depending on the type of cancer, tumor size, location, overall health of the patient, age, and whether the patient is having other types of treatment.
The two types of radiation include:
- External Beam Radiation Therapy – This is where radiation is delivered from outside the body and directed at the cancer site of a patient. There are different systems that produce different types of radiation for external beam therapy including orthovoltage x-ray machines, linear accelerators, cobalt-60 machines, neutron beam machines and more. A radiation oncologist decides on the type of system best suited for each cancer patient. External beam radiation therapy is used for most cancer patients to treat many types of tumors including cancers of the breast, colon, lung, head and neck area, and prostate cancer.
Different levels of radiation are used depending on the location of the tumor. Low-dose radiation is used to treat surface tumors like skin cancer. Stereotactic radiation therapy focuses the radiation beam on small areas where it delivers very high doses. It targets the tumor from different directions to deliver radiation directly to the tumor while minimizing exposure to areas surrounding it. The procedure is painless and patients can go home and continue with normal activities.
- Internal Radiation Therapy – Also called brachytherapy, this involves placing radiation sources close to the tumor site or inserting them into the tumor. The radioactive sources are in form of seeds, rods or wires. Internal radiation technique is effective in treating cancers of the rectum, cervix, vagina, eye, uterus and some head and neck cancers. It is also used to treat cancers of the skin, breast, anus, brain, lung, esophagus, bladder, and the prostate.
In some instances, brachytherapy may be used in combination with external beam therapy to destroy cancerous cells surrounding the tumor in a large area and to destroy the main concentrated mass of tumor cells. The various types of brachytherapy include interstitial brachytherapy, intraluminal radiation therapy, intracavitary brachytherapy and radioactively tagged molecules that are administered intravenously. The radioactive sources can be put in the body and taken out the same day or they can stay in the body for several days or even permanently.
Radiation therapy is used to ease cancer symptoms and treat cancer. When used in cancer treatment, radiation therapy can cure cancer, stop or slow its growth and prevent it from recurring. Treatments that ease symptoms are known as palliative treatments. Radiation therapy can be used alongside other cancer treatment options such as chemotherapy, immunotherapy, and surgery.