How is radiation therapy used to treat cancer?

The goal of radiation is to destroy or damage cancer cells in the area being treated while doing as little harm as possible to surrounding, healthy tissue. There are different types of radiation therapy or treatment and different ways to deliver it to the tumor site. These differences are based on the type of cancer, how deeply the beams of radiation need to penetrate, and for how long.

There are two basic forms, external beam radiation and internal beam radiation. External beam radiation enters the body from equipment positioned outside. Internal beam radiation (also called brachytherapy) is less common and consists of placing the radiation source inside the body. For prostate cancer, this treatment is done by placing radioactive “seeds” inside the prostate to directly treat the tumor site. Forms of brachytherapy are also used for some breast cancer patients using the Mammosite technology and for a number of other cancer diagnoses. Some form of radiation therapy is used by about half of cancer patients, either with other treatments or alone.

Doctors treat cancer in a variety of ways including surgery, chemotherapy and radiation.

Radiation therapy (also know as radiotherapy, cobalt therapy, X-ray therapy or irradiation) fights cancer because it can destroy cancer cells more easily than normal cells. Typically, radiotherapy is delivered with an external beam of gamma rays, x-rays or alpha and beta particles directed at the cancerous tumor. Radioactive wires or pellets can be used internally. They are put inside a tiny container and implanted in the body near the tumor. Sometimes, both internal and external radiation is used.

Radiation therapy is commonly used to treat early Hodgkin's lymphoma, certain cancers of the lung, bladder cancer, prostate cancer and other tumors. Radiation therapy is commonly used with other therapies, including chemotherapy and surgery. For instance, radiation therapy may shrink a tumor to make surgery easier or, it may be used after surgery to prevent a tumor from reforming. Sometimes, radiation therapy is used alone, especially if a particular tumor is more susceptible to radiation. Radiation also might be used alone when surgery to the specific area is too risky. Even when a cure is highly unlikely, radiation can help shrink a tumor to provide relief from symptoms that come from a tumor's growth.

Radiation therapy can be used to shrink a colon cancer tumor in certain cases. It can also be used to treat lymph nodes that are affected by cancer. The use of radiation therapy depends on the type of cancer, including its location and stage.

Because radiation can destroy cancer cells, external beam radiation therapy may be used to:
  • Remove cancer
  • Ease pain by shrinking a tumor
  • Help prevent cancer from coming back
  • Help other cancer treatments work better
Radiation is often combined with surgery, chemotherapy, or both.
Dr. Nimesh P. Nagarsheth, MD
Gynecologic Oncologist
There are two basic kinds of radiation therapy. External beam uses high-energy radiation to target a specific area, and brachytherapy uses radioactive materials placed near the tumor. Both kinds of radiation are used to treat cancers throughout the human body. These treatments serve to shrink tumors and eliminate cancer cells. Radiation therapy is associated with several potential side effects depending on which part of the body it is prescribed for, and depending on the goal of treatment. Please ask your radiation oncologist for a review of the risks and benefits of radiation therapy as it pertains to your specific case before starting any treatment.
Music And Cancer: A Prescription For Healing

More About this Book

Music And Cancer: A Prescription For Healing

From diagnosis to end-of-life care to the meaning behind life with cancer, Music and Cancer: A Prescription for Healing is designed to improve the quality of life of people affected by cancer in a...

Continue Learning about Radiation Therapy For Cancer

Can I drive to my radiation treatments for cancer?
Riverside Cancer Care CenterRiverside Cancer Care Center
Radiation therapy is usually given on an outpatient basis. Most patients will feel well enough t...
More Answers
How do you prevent radiation from damaging healthy cells?
Afshin Rashtian, MDAfshin Rashtian, MD
Doctors avoid harming healthy tissue by deciding where to target radiation before cancer treatment. ...
More Answers
What kinds of radiation treatments are there for cancer?
Penn MedicinePenn Medicine
Even if a doctor surgically removes all the cancer that can be seen at the time of an operation, you...
More Answers
How Can Cancer Treatment Affect My Sexual Health?
How Can Cancer Treatment Affect My Sexual Health?

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.