Radiation Therapy for Prostate Cancer

Radiation therapy uses high-energy particles to kill cancer cells. This procedure may cure some people with early-stage prostate cancer. It may also relieve symptoms for people with advanced prostate cancer.^1,2

Different types of radiation therapy have different risks and benefits. Talk to your doctor about the right treatment for you. Your doctor can suggest ways to reduce risks during and after treatment.¹

What is radiation therapy?

Radiation therapy involves high-energy X-rays. These X-rays interfere with DNA in cancer cells. This can kill cancer cells or prevent them from multiplying. Radiation therapy slows cancer growth and can cure certain forms of cancer.²

But X-rays can release energy before they hit their target. This can damage healthy tissues near the prostate. Damage to healthy tissues can cause side effects. Newer techniques and strategies are improving radiation therapy. The ultimate goal is to target cancer cells while avoiding healthy cells.^1,2

How does radiation therapy work to treat prostate cancer?

Radiation therapy is used in several ways to treat prostate cancer. How it is used depends on the cancer stage and other factors. Radiation therapy may be used:¹

• As the first treatment and potential cure for lower-risk prostate cancer that has not spread
• With hormone therapy as the first treatment for higher-risk prostate cancer that has not spread outside the prostate, or for cancer that has spread close to the prostate
• After surgery if cancer is not completely removed or if it comes back
• To relieve symptoms if the cancer has spread to bones

Radiation therapy has a similar cure rate as radical prostatectomy for cancer that has not spread beyond the prostate. Over 85 percent of people with low-risk prostate cancer may live for at least 10 years without cancer returning after receiving certain forms of radiation therapy or radical prostatectomy.^1,2

Examples

The 3 main types of radiation therapy used for prostate cancer are:^1-3

• External beam radiation therapy (EBRT)
• Brachytherapy (internal radiation)
• Radiopharmaceuticals

External beam radiation therapy (EBRT)

EBRT involves radiation beams coming from outside the body. Before treatment, your doctor will use imaging tests to see where the cancer cells are. Modern techniques focus radiation on the tumor better than in the past. This allows doctors to use higher doses of radiation while trying to minimize side effects.^1-3

EBRT is typically given up to 5 days a week for several weeks. Treatment is painless and lasts a few minutes. It takes longer to position your body before treatment.¹

Common EBRT techniques include:^1,2

• Three-dimensional conformal radiation therapy (3D-CRT) – This uses computers to map the prostate and aims radiation beams from all directions.
• Intensity modulated radiation therapy (IMRT) – IMRT is a more advanced form of 3D-CRT.
• Image-guided radiation therapy (IGRT) – This technique uses images taken just before treatment to make sure the location of the prostate has not changed.
• Volumetric modulated arc therapy – This is a variation of IMRT that uses a rotating machine.
• Stereotactic body radiation therapy (SBRT) – SBRT gives larger doses over fewer sessions.
• Proton beam therapy – This therapy uses protons instead of X-rays, which may cause less damage to healthy tissues.

IMRT is the most common type of EBRT used for prostate cancer. It is often used with IGRT. But SBRT might be a better option for some people. More research is needed on newer techniques.^1,2

Brachytherapy (internal radiation therapy)

Brachytherapy is also called seed implantation or interstitial radiation therapy. It uses small radioactive pellets placed directly into your prostate. It is typically used alone only for people with early-stage, low-risk prostate cancer.^2,3

There are 2 types of brachytherapy for prostate cancer:^1,2

• Permanent low dose rate (LDR) brachytherapy – About 100 pellets of radioactive material (such as iodine-125) are inserted. They give off low doses of radiation for weeks or months.
• Temporary high dose rate brachytherapy – Catheters are inserted to deliver radioactive elements to the cancer. This may occur a few times over 2 days, for 5 to 15 minutes each time.

LDR is more common. In both techniques, radioactive material is implanted in the prostate using needles inserted between the scrotum and the anus. An imaging test may be used to help guide the placement. You will receive anesthesia during the implantation process.¹

Radiopharmaceuticals

These drugs are radioactive elements injected into a vein. They travel through the blood to reach cancer cells. They then give off radiation that kills cancer cells. Radiopharmaceuticals can generally reach cancer cells anywhere in the body.^1,3

The 2 types of radiopharmaceuticals used to treat prostate cancer are:¹

• Drugs that target prostate-specific membrane antigen – Pluvicto® (lutetium Lu 177 vipivotide tetraxetan)
• Drugs that target bones – Xofigo® (radium-223), Metastron® (strontium-89), or Quadramet® (samarium-153)

What are the possible side effects?

Side effects can vary depending on the specific type of radiation therapy you are getting. Common side effects of EBRT and brachytherapy include:^1,2

• Bowel irritation, which can cause diarrhea, bloody stool, and leakage
• Bladder inflammation, which can cause urinary problems
• Narrowing of the urethra
• Erectile dysfunction
• Fatigue
• Fluid retention and swelling

Common side effects of radiopharmaceuticals include:¹

• Fatigue
• Dry mouth
• Nausea
• Loss of appetite
• Constipation
• Low blood cell counts
• Kidney damage

These are not all the possible side effects of radiation therapy. Talk to your doctor about what to expect when getting radiation therapy. You also should call your doctor if you have any changes that concern you when getting radiation therapy.

Other things to know

Your doctor will determine the best treatment strategy for you, including dose, type, and schedule. A team of radiation specialists and other doctors will work together.¹

Talk to your doctor about precautions to take during radiation therapy. Your doctor can suggest ways to reduce risk and keep other people safe. These may include:¹

• Staying away from pregnant women and small children
• Straining urine for seeds after LDR brachytherapy
• Adjusting fluid intake
• Following a specific diet to avoid bowel problems

Before beginning treatment for prostate cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.