What Is Radiation Therapy? A Guide to Radiotherapy Treatment, Types, and Side Effects

Radiation therapy, also called radiotherapy, is one of the main types of treatment for cancer.  Over half of patients with cancer will undergo radiation therapy at some point during their cancer treatment. It’s helpful to know about the types of radiation therapy and possible side effects from it. Here, we’ll provide an overview of these types and how they work.

What is radiation therapy? 

Radiation therapy usually refers to X-ray therapy. The radiation used for radiation therapy is similar to what is used for imaging studies such as X-rays and CT scans.  However, radiation therapy uses higher-energy X-rays. Also, the X-ray doses for cancer treatments are much higher than the doses used for imaging tests.

Radiation oncologists are doctors who are trained to treat cancer with radiation therapy.  They work with other doctors to decide when and how to use radiation therapy to treat a person with cancer.

Radiation therapy plays a role in the treatment of many different cancers, including (but not limited to):

• Prostate cancer

• Breast cancer

• Lung cancer

• Colorectal cancer

• Hodgkin lymphoma

• Non-Hodgkin lymphoma

• Uterine cancer

• Head and neck cancer

• Brain tumors

• Skin cancer

How does radiation therapy work to fight cancer?

Radiation therapy kills cancer cells by damaging their DNA, or genetic material. When their DNA is disrupted, cancer cells can no longer grow or spread.

Radiation therapy can play several different roles in cancer treatment:

• Radiation therapy is used to cure certain types of cancer (such as localized prostate cancer and some types of lymphoma). In some of these cases, radiation is combined with chemotherapy.

• In other cases, doctors prescribe radiation therapy after cancer surgery to reduce the risk of the cancer coming back. 

• Finally, radiation therapy may be used to relieve cancer-related symptoms, such as pain.

Radiation oncologists develop an individualized radiation treatment plan for each person. The details of the plan depend on the type of cancer, its stage, the location of the tumor, and how close it is to normal tissues.

What are the different types of radiation therapy?

There are two main types of radiation therapy: external beam radiation therapy (EBRT) and internal radiation, called brachytherapy. The most common type is EBRT.  

In EBRT, a beam of radiation is directed at a tumor from outside the body.  There are several types of EBRT, including:

• 3-D conformal radiation therapy (3D-CRT)

• Intensity modulated radiotherapy (IMRT)

• Superficial X-ray therapy

• Stereotactic radiation therapy

• Electron therapy

• Proton therapy

• Neutron therapy

• Carbon ion therapy

To protect nearby healthy tissues, a course of EBRT is often broken up into several “fractions” instead of being delivered all at once. An EBRT course may range in duration from 1 treatment to over 40 treatments.  Radiation treatments are most often delivered on a daily basis (Monday through Friday).

By comparison, brachytherapy refers to placing radioactive material directly into (or up against) a tumor. It is commonly used to treat prostate, breast, gynecologic, and skin cancers. Brachytherapy is often completed in just one treatment, although some cases need multiple treatments.

What does radiation therapy feel like?

During EBRT, people don’t feel or see anything. Receiving an EBRT treatment is similar to getting an X-ray or CT scan.

Brachytherapy, on the other hand, usually requires a brief procedure to accurately place the radioactive source. Depending on the type of cancer, a brachytherapy procedure may be done in an operating room with anesthesia. You can’t feel the actual radiation, however.

What are some side effects of radiation therapy, and how do you cope with them?

Side effects of radiation therapy depend on the part of the body being treated, the radiation dose, and what tissues and organs are nearby. Most people who get radiation therapy have mild to moderate side effects.

The prostate gland, for example, is next to the bladder and the rectum. As a result, the most common side effects of prostate radiation involve these organs. Men undergoing prostate radiation often experience irritation with urination and bowel movements.

Radiation therapy can also cause fatigue, regardless of the part of the body being treated. Typically, this fatigue is mild, and people can continue their normal activities. Most people getting radiation are able to exercise, work, and spend time with friends and family. Getting plenty of sleep, eating and drinking well, and staying active are all helpful ways to manage fatigue from radiation.

Finally, radiation therapy can cause skin irritation in the area of treatment. This skin irritation is usually mild. Radiation burns (when the skin blisters or peels) are uncommon. Careful skin care can help with these side effects. In some cases, doctors may prescribe a cream or lotion, like hydrocortisone, to treat skin irritation from radiation.

If radiation exposure is harmful, why is it prescribed as a treatment?

Although radiation can harm certain organs and tissues, it’s also an effective treatment for cancer. Fortunately, there are many ways to avoid or reduce the side effects of radiation therapy. Radiation oncologists are experts in using radiation to treat cancer with the fewest side effects possible.

If I receive radiation therapy, can I give another person radiation sickness?

In most cases, people who get radiation therapy aren’t dangerous to others. 

In EBRT, radiation passes through the body instantaneously. There is no radiation left in the body when treatment is completed.

But with some brachytherapy treatments, radioactive material is left in the body. In these cases, doctors recommend precautions to protect others from radiation exposure. These precautions are typically easy to follow and only last for a few days or weeks.

The bottom line

Radiation therapy is an important part of treatment for many types of cancer. It may be used to cure certain cancers, and it’s often used together with surgery and chemotherapy.  

Radiation therapy is generally safe. Side effects of radiation therapy depend on the part of the body being treated and the radiation dose.

Why trust our experts?

Written by:

David Marcus, MD

David Marcus, MD, is a board-certified radiation oncologist with expertise in the management of many types of cancer, including prostate cancer, breast cancer, and several others. He earned his medical degree at Emory University in Atlanta, Georgia, where he also completed residency training in radiation oncology.

Edited by:

Mandy Armitage, MD

Mandy Armitage, MD, has combined her interests in clinical medicine with her passion for education and content development for many years. She served as medical director for the health technology companies HealthLoop (now Get Well) and Doximity.

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