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Prostate Cancer: External-Beam Radiation Therapy

Prostate cancer may be treated with radiation therapy. It is also called radiotherapy. It works by sending radiation to the cancer sites. This can kill cancer cells or stop them from growing. 

There are 2 types of radiation therapy for prostate cancer:

  • External-beam radiation therapy (EBRT). This type of therapy uses a machine similar to an X-ray machine to deliver radiation to your prostate

  • Internal radiation or brachytherapy. This type of therapy uses tiny radioactive seeds or tubes put into your body to send radiation to your prostate

You may be treated with one or both types of therapy.

If you are going to get radiation therapy, a radiation oncologist will create a treatment plan for you. This is a doctor who specializes in treating cancer with radiation therapy. Each person’s treatment plan is different. Your plan will include the type of radiation you will have. It will also include how often and for how long you will have the treatment.

Why might I need radiation therapy?

Your healthcare provider may advise radiation therapy if:

  • You have a slow-growing cancer that has not spread outside your prostate gland. 

  • You had surgery for prostate cancer, but there are signs the surgery might not have removed all of the cancer.

  • You have had surgery but your cancer has come back.

  • You have a cancer that has grown outside the prostate but has not reached the lymph nodes or distant organs. (In this case, radiation therapy might be used along with hormone therapy.)

  • You have advanced prostate cancer that is causing symptoms, such as pain in your bones. EBRT may shrink the cancer and help relieve your pain.

Types of EBRT

Some of the types of EBRT that can be used to treat prostate cancer include:

  • Standard. Standard EBRT aims radiation at your prostate from one direction. This is much like getting an X-ray, only it lasts longer. This type of ERBT is rarely used anymore.

  • 3-D conformal radiation therapy. This approach aims radiation at the prostate from several directions. This can lessen the side effects on healthy tissue. 

  • Intensity-modulated radiation therapy (IMRT). IMRT uses a computer to control both the direction and the strength (intensity) of the radiation reaching the prostate. This also can lessen the side effects on healthy tissue.

  • Proton beam therapy. This newer type of treatment uses protons instead of X-rays. Protons do less damage to normal, healthy cells as they pass through them, and then stop after a certain distance. This might lead to fewer side effects. But so far, this approach has not been shown to be safer or more effective than other types of EBRT. Proton therapy is only available in a small number of centers around the country.

Getting ready for EBRT

Before having EBRT, you may have a lymph node biopsy to see if your cancer has spread outside the prostate gland. One or more lymph nodes are removed to see if they contain cancer. Other tests may also be done.

Before your first treatment, you’ll have an appointment to plan for the treatment. This is called simulation. During this appointment:

  • You’ll lie on a table while a radiation therapist uses a machine to find exactly where the radiation will be aimed. The therapist may mark your skin with tiny dots of permanent ink. These are used to aim the radiation at the exact same place each time.

  • You may also have CT scans or other imaging tests to help locate the cancer.

  • A plastic mold of your body may be made for some types of ERBT. The mold helps you stay in the same position for each treatment.

What to expect for your treatment

You will receive ERBT at a hospital or clinic. You will likely not have to stay overnight. The total length of time for your treatment depends on the type and dose of radiation, as well as why you are getting it. For example, if you are getting radiation as the main treatment for an early-stage prostate cancer, you will likely get treatments 5 days a week for several weeks in a row. If you are getting radiation therapy to treat bone pain, you will probably have fewer treatments.

Each treatment is similar to getting an X-ray, although the radiation is stronger. You lie on a table while the machine delivers the radiation. The actual treatment is painless and typically lasts for only a few minutes, although getting you into the proper place for treatment each time takes longer.

Your radiation oncologist or nurse can tell you what to expect during treatment.

What happens after EBRT?

After you finish your radiation therapy, your oncologist and other healthcare providers will closely watch your health. You will have regular lab tests and scans. Make sure you tell your health care providers about any symptoms you have. Make sure to go to all of your follow-up appointments.

Side effects of EBRT

Radiation therapy affects normal cells, as well as cancer cells. This can cause side effects. The side effects depend on the amount and type of radiation. Some side effects may occur during treatment. Others may occur in the weeks or months after EBRT. Side effects of radiation therapy to the prostate may include:

  • Feeling tired

  • Redness, flaking, or fluid on the skin near the treatment area

  • Loss of hair, especially pubic hair

  • Swelling of your penis, scrotum, or legs (rare)

Radiation to the prostate can irritate the bladder or intestines. This can lead to side effects like:

  • Diarrhea or intestinal cramping

  • Blood in your stool

  • Feeling the need to urinate often

  • Burning feeling when you urinate

These side effects can sometimes start during treatment. They often go away over time. But in some men they might not go away fully. Some men might also have trouble controlling urine flow (incontinence) in the months or years after treatment.

Talk with your healthcare providers about any side effects you have. They may be able to help lessen them.

Erectile dysfunction after treatment

Another possible side effect after radiation therapy is problems with erections (erectile dysfunction or impotence). The risk of this depends on many factors, including a man's age and ability to have erections before treatment. After radiation therapy, erection problems tend to develop slowly over time and can get worse over about 2 years. This is different from surgery, where erection problems tend to happen right away but can often get better over time. 

Online Medical Reviewer: Alteri, Rick, MD
Online Medical Reviewer: Cunningham, Louise, RN
Date Last Reviewed: 6/1/2018
© 2021 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare provider's instructions.