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Radiation therapy, or radiotherapy, uses various forms of radiation to safely and effectively treat prostate cancer. It works by damaging the genetic material within the prostate cancer cells and limiting their ability to successfully reproduce. When these damaged cancer cells die, the body naturally eliminates them.

Types of radiation therapy

Radiation therapy can be given externally (directed from outside the body) or internally (placed inside the body). 

External Beam Radiation Therapy (EBRT)

Involves treating the prostate and the pelvic region with radiation in daily doses. Most EBRT is delivered using x-ray photons (with the exception of proton beam therapy). This radiation is the same kind used for an X-Ray or CT scan, except that the amount of energy used is much higher. 

Internal Radiation Therapy

Comes in two types: brachytherapy and radiopharmaceuticals. Although they both involve placing radioactive materials inside the body, they are different options, used for different stages of the disease. Both low and high dose brachytherapy are used for localized prostate cancer. Scroll down the page to learn more about brachytherapy. 

Radiopharmaceuticals are a medicine used to treat prostate cancer that has spread, or metastasized, to the bone. Scroll down to learn more about radiopharmaceuticals.

In the video below, Dr. Benjamin Lowentritt discusses radiation treatment for prostate cancer:

Radiation therapy in localized disease:

For men that need treatment for localized prostate cancer, EBRT and brachytherapy can be alternatives to surgery. Radiation therapy is as effective as surgery when used to cure prostate cancer.

At this stage of disease, radiation therapy is used to attempt to cure the disease. However, it is also sometimes used if surgery didn’t completely remove the cancer, or it came back in the area of the prostate after surgery.

These treatment options may require multiple visits. As always, it is important to consider costs and potential side effects.

Radiation therapy in advanced disease:

Some forms of EBRT can help with advanced prostate cancer. One type of external radiation therapy is used along with hormone therapy to treat cancer that has spread outside the prostate to nearby tissue. Radiopharmaceuticals are used to treat metastatic prostate cancer to the bone.

Watch our expert medical oncologist, Dr. Alicia Morgans from Dana-Farber Cancer Institute, discuss EBRT used to manage pain and symptoms of bone metastases:

How does external beam radiation therapy work?

All external beam radiation therapy (EBRT) is done on an outpatient basis. EBRT uses a machine to direct high-energy X-rays at the cancer in daily doses. Using software, your treatment team controls the size and shape of the beam as well as how it is directed at your body to most effectively treat your tumor and minimize damage to surrounding normal tissue.

Treatments are typically given five days a week over a period of several weeks, depending on the type of EBRT. New technology or techniques allow the radiation to focus more precisely on the tumor. This reduces radiation exposure to nearby health tissues while allowing a higher dose of radiation directly to the tumor.

Who should consider external beam radiation therapy?

In most cases, EBRT is used to treat localized prostate cancer (confined to the prostate). Sometimes it is used in more advanced cases. It can be used along with hormone therapy for tumors that have grown outside the prostate and into nearby tissues. It is also sometimes used to relieve pain from bone metastases.

What are the different types of external beam radiation therapy?

Many of the techniques noted below use technology to direct the treatment to target the cancer. Each type of external beam radiation starts with a CT scan to “map” your body and custom tailor the radiation to your specific anatomy. Special computers are then used to plan radiation treatment to deliver an adequate dose to the prostate while sparing nearby organs, such as the rectum and bladder, as much as possible.

Three-Dimensional Conformal Radiation Therapy (3D-CRT)

3D-CRT uses imaging tools like CT or PET scans to precisely map the tumor before treatment. Photon radiation is then delivered to effectively target the tumor, but may affect a small amount of normal tissue such as the bladder or rectum. Therefore, 3D-CRT tends to be less favored today due to newer techniques that may result in fewer side effects.

This type of external radiation therapy can also be used to relieve pain and other symptoms in metastatic prostate cancer.

Intensity Modulated Radiation Therapy (IMRT)

IMRT allows for the radiation dose to conform more precisely to the tumor by controlling or modulating the intensity of the radiation beam. The radiation beams can be broken up and their strength adjusted individually. This allows doctors to safely deliver a higher dose of radiation to the tumor directly, while delivering lower doses to the healthy tissue nearby. Internal markers to track the prostate during treatment (called fiducials) may be used, such as Calypso. Your body may be immobilized in order to keep you from moving during treatment.

There are several types of IMRT available from various LINAC manufacturers, such as Tomotherapy (Accuray) and volumetric modulated arc therapy (VMAT; Varian and Electa).

Image Guided Radiation Therapy (IGRT)

IGRT is a form of IMRT. With IGRT, CT scans are taken both during the planning process and just before treatment begins. Comparing the two images allows doctors to adjust treatment as needed, since tumors can move between treatments. This allows precision targeting of the cancer while avoiding nearby healthy tissue. In some cases, doctors will implant tiny markers (called fiducials) in or near the tumor to pinpoint it for IGRT to account for organ/tumor motion even if the body is immobilized.

Calypso is another form of IGRT where the prostate can be tracked during the treatment.

Stereotactic Body Radiation Therapy (SBRT)

SBRT, also called Stereotactic Ablative Radiotherapy (SABR), is a form of IGRT. SBRT is used to deliver high doses of radiation to a precise area in the prostate using specialized techniques not achievable by standard conventional radiation therapy. This allows the total dose of radiation to be given in 5 treatments over 1-2 weeks rather than the typical 20-44 treatments over several weeks used for other types of external radiation therapy.

The radiation beam needs to be extremely accurate in order to limit the side effects on healthy tissue. During treatment, the body immobilization used is often more restrictive than with IMRT due to the high doses of radiation.  Fiducials, or internal prostate markers, are often used in this type of treatment.

Cyberknife and Truebeam are two types of LINACs used for SBRT treatment of prostate cancer.

Proton Beam Radiation Therapy

Proton therapy is a very precise cancer treatment that uses a different type of radiation than the other types of external radiation therapy.  Instead of photons, this type of radiation uses protons, which have special physical properties.  Protons act like a “depth charge” in that at a certain depth in the body they release a high dose of radiation. The radiation does not go beyond this depth (no “exit dose”) which may decrease exposure to normal tissues.

Clinical trials to evaluate proton beam radiotherapy are still ongoing. It is often viewed as experimental, and insurance companies may not cover it.

MRI-Guided Radiation Therapy (MRgRT)

A recent development is real-time MRI-guided radiation therapy (MRgRT). MRI provides excellent prostate visualization for accurate and precise dose delivery to the tumor and avoidance of radiation to surrounding healthy tissue. MRI visualization eliminates the need for implanted fiducial markers and enables the use of MRgRT for SBRT in 5 or fewer sessions. 

With MR-guided radiation therapy, a new MRI scan is acquired for each treatment, and a personalized plan is developed to fit the patient’s anatomy that day.

MRIdian is a type of MRI-guided radiation therapy. When the prostate or nearby sensitive organs like the rectum and bladder change position during treatment, MRIdian automatically turns the radiation beam off. When the organs return to the correct position, the radiation beam automatically turns back on, and treatment continues.

What are the side effects of external beam radiation therapy?

As with most prostate cancer treatments, EBRT can also cause side effects. The severity can depend on the type of radiation, dose size, length of treatment, and area of treatments. These may include:

If you are considering prostate cancer treatment with a form of EBRT, talk with your radiation oncologist to discuss options, potential side effects, and how those side effects will be managed.

Recently, the FDA approved the use of Space OAR, a hydrogel product for men choosing radiation therapy that can reduce the radiation received by the rectum during treatment. This can help decrease the chances of developing rectal complications such as the inability to control your bowels. The hydrogel is injected between the prostate and rectum where the gel solidifies and creates a space before radiation begins. To learn more about this product, visit the manufacturer’s site.

What are the different types of internal radiation therapy?

Brachytherapy and radiopharmaceuticals are both considered internal radiation therapies because they both work after being inserted inside the body, rather than being directed from outside. However, the similarities mostly end there. Brachytherapy works by implanting radioactive material into the prostate and is used for localized prostate cancer. Radiopharmaceuticals are injected into the bloodstream and are used for advanced, metastatic prostate cancer. Read on to find the details of each.

How does brachytherapy work?

Brachytherapy involves implanting small, permanent radioactive seeds or temporary needles into the cancerous prostate.

After you are identified as a good candidate for brachytherapy, an ultrasound is used to guide the placement of needles into the prostate. Depending on whether you and your doctor have chosen permanent/low-dose brachytherapy or temporary/high-dose brachytherapy, these needles are then used to either put in permanent seeds or temporary radiation sources.

Placement of seeds is a minimally invasive procedure and does not require incisions. Men undergoing the procedure can return to full activity in less than a week. This is done as an outpatient procedure before you begin treatment.

Permanent or Low-Dose Brachytherapy (LDR)

In this procedure, small metal seeds are placed into the prostate. These seeds are permanently placed into the prostate and gradually deliver the radiation to the prostate over several months. Once the radiation is lost, the seeds remain in the prostate. They are harmless and should not bother you.

There are different types of radioactive seeds used, such as I-125 (radioactive iodine) and Pd-103 (radioactive palladium), which release radiation at different rates.

Temporary, or High-Dose Brachytherapy (HDR)

In this procedure, catheters are placed into the prostate while the patient is under anesthesia. After a scan of the prostate is used to plan the radiation treatment, small radioactive sources are moved through each of the catheters. Once the treatment is complete, the tubes are removed.

This type of brachytherapy is generally given over several treatments. Once treatment is over, there is no radioactivity left in your body. Unlike in permanent/low-dose brachytherapy, there is no need to take special precautions around others after treatment.

What are the side effects of brachytherapy?

  • Frequent urination or urinary retention or burning with urination
  • Erectile dysfunction
  • Urethral stricture or narrowing of the urethra
  • Diarrhea or blood in the stool
  • Secondary cancers

For the short time that the seeds are giving off larger amounts of radiation, you should avoid close proximity to children or pregnant women. Make sure to talk with your radiation oncologist or oncology nurse for instruction about radiation safety and exposure for family members or pets.

If you are traveling through an airport following brachytherapy treatment, there is a chance that radiation detectors will be set off. Talk to your radiation oncologist and ask for a note to indicate you’ve just had radiation treatment.

Who should consider taking radiopharmaceuticals?

Radiopharmaceuticals are given through a vein to men with metastatic prostate cancer that has spread widely to the bone. Strontium89 and Samarium-153 are radiopharmaceuticals given to reduce the pain caused by the bone cancer. Radium-223, or Xofigo®, is a radiopharmaceutical given to prolong life.

The side effects associated with radiopharmaceuticals are mainly the suppression, or lowering, of white blood cell and platelet levels in the blood. Your doctor will be able to assess whether your body can handle this side effect before you are given the treatment and will monitor your levels after you receive it. Your doctor, specialist nurse, or nuclear medicine practitioner will be able to give you more information about the treatment and possible side effects.

If your doctor has told you that your bone metastases (“bone mets”) have spread, you may be a candidate for a radiopharmaceutical. Speak with your oncology team to see if one of these treatments may be right for you.

What are the side effects of radiopharamaceuticals?

  • Nausea
  • Diarrhea
  • Vomiting
  • Swelling of the leg, ankle, or foot

Your doctor, specialist nurse, or nuclear medicine practitioner will be able to give you more information about the treatment and possible side effects.

In the following videos, our expert medical oncologist, Dr. Alicia Morgans from Vanderbilt-Ingram Cancer Center, speaks more about internal radiation therapy, called radiopharmaceuticals, and explains the findings of the recent ASLYMPCA clinical trial on the use of Radium-223 in prostate cancer patients: