Prostate Cancer: Radiation Therapy

Written by Evan Starkman, Stephanie Langmaid
Medically Reviewed by Shruthi N, MD on June 16, 2025
11 min read

Radiation therapy, also called X-ray therapy, uses high levels of radiation to kill prostate cancer cells or stop their growth, with minimal damage to healthy cells.

Radiation can be given from a machine outside the body and aimed at the prostate (external radiation). Or a surgeon can place radioactive materials into the tumor (internal radiation or brachytherapy). These radioactive materials can be temporary (removed after the proper dose is reached) or permanent.

Your doctor might recommend prostate radiation therapy in several situations.

It can be the first treatment for cancer that hasn't spread outside your prostate gland and is “low-grade.” The grade is a number that tells you how abnormal your cancer cells look under a microscope. Lower grades mean cells look more normal, and the cancer is likely to grow more slowly.

Radiation, along with hormone therapy, might also be part of your first cancer treatment if the disease has spread beyond your prostate into nearby tissues.

If you get surgery for prostate cancer, your doctor might recommend you get radiation therapy afterward — especially if the surgeon couldn’t remove all of the cancer or if the cancer returns in the area of your prostate.

If you have advanced prostate cancer, radiation could help keep the disease under control for as long as possible. It can also help prevent or ease symptoms that the cancer might cause.

With external beam radiation therapy (EBRT), sophisticated machines shape beams of radioactive particles so that they can precisely target a prostate tumor while minimizing damage to surrounding tissue. This technology is called conformal or 3D conformal radiotherapy.

This method has replaced conventional 2D technology, which delivers beams in a box shape and can harm a lot of healthy tissue. Now, even more advanced techniques have been developed.

Intensity-modulated radiotherapy (IMRT)

This is the EBRT technique used most often in prostate radiation therapy. 

It uses computer-generated images to plan and deliver tightly focused radiation beams to prostate cancer tumors. It lets your treatment team adjust the beam's intensity to "paint" a precise radiation dose onto the shape and depth of the tumor. 

Because your prostate can move a bit inside your body as you breathe or digest, and because your body's shape and size can change during the treatment period, you may have imaging done immediately before each treatment. Or your doctor may use a machine with built-in imaging that stops if your prostate moves out of the target field. This is called image-guided radiation therapy (IGRT) or MRI-guided radiation therapy.

Stereotactic body radiation therapy (SBRT)

Also called stereotactic ablative radiation therapy (SABR), this method uses imaging guidance to deliver a very large dose of radiation to a very specific place in the prostate. The entire treatment is usually done in just a few days. 

This method may not be right for you if your prostate is very large.

Proton beam radiation therapy

This type of therapy treats tumors with protons instead of X-ray radiation. These particles operate differently from photons, the type of particle found in conventional X-rays. Protons release their radiationonly after they've traveled a certain distance, meaning they don't harm the tissue they pass through on the way to or past the tumor. That can mean fewer side effects.

Proton beam therapy might be a safe treatment option when a doctor decides that using X-rays could be risky for a patient. But it isn't widely available, and not all health insurance plans cover it. 

Internal radiation therapy for prostate cancer is also delivered through several methods.

Brachytherapy

For this prostate radiation treatment, a surgeon places radioactive pellets (also called "seeds") about the size of a grain of rice directly into your prostate. They use imaging tests to help them place the pellets correctly and computer programs to figure out the exact dose of radiation you need.

In general, getting brachytherapy alone is only an option for some people with early-stage prostate cancer that's growing relatively slowly. Brachytherapy plus external radiation might be an option if your cancer is more likely to grow outside your prostate gland.

The two types of brachytherapy for prostate cancer are:

Permanent brachytherapy. Your doctor may also call this "low dose rate" brachytherapy. The pellets give off low doses of radiation for weeks or months. They're very small and rarely cause pain, so doctors usually leave them in your prostate after they stop giving off radiation.

Temporary brachytherapy. Your doctor may also call this "high dose rate" brachytherapy. Doctors don't use it as often as the permanent type. Temporary brachytherapy gives off higher doses of radiation for a short time. In general, you need up to four quick treatments over two days, and your treatment team removes the radioactive material each time.

Radiopharmaceutical treatments

Radiopharmaceuticals, or medicinal radiocompounds, are a group of pharmaceutical drugs containing radioactive isotopes. They're used to treat patients diagnosed with castration-resistant metastatic prostate cancer. They help control the cancer and keep it from spreading further.

If you get external radiation therapy, you'll need to get regular sessions (generally five days per week) during a period of about five to eight weeks. The exact schedule and procedure may vary depending on the type of prostate radiation treatment you receive.

Before treatment

You'll first go through a planning process that can take a couple of weeks. Members of your care team will give you imaging tests to map the exact shape, size, and location of your prostate and see if any other tissue also needs radiation. This may include a conventional X-ray, CT scan, MRI, PET scan, or a combination of these.

A computer calculates the exact dosage and targets for the radiation machine to help your care team plan your treatment.

A technician may make a special mold for you to lie in during treatments. It's like a big beanbag that hardens into the shape of your body to help you stay in the right position and hold still.

To help guide the beams, you may get small marks tattooed on your skin or markers implanted inside your prostate. You may also have a special gel injected under your skin between your prostate and rectum to help block radiation from damaging your rectum.

During treatment

For each treatment, the radiation therapist will help you onto the treatment table and into the correct position. Then, they'll leave the room and start the radiation treatment.

They'll watch you closely during the treatment. Cameras and an intercom are in the treatment room, so the therapist can always see and hear you. Try to stay still and relaxed during treatment. Let the therapist know if you have any problems or if you feel uncomfortable.

The treatment machine will move around you to deliver radiation from different angles. It will be loud, but it won't touch you, and you'll feel nothing during the treatment. Once the treatment is finished, the therapist will help you off the treatment table.

You'll be exposed to the radioactive beams for just a few minutes, and the whole process usually takes less than an hour.

Different types of prostate radiation therapy can cause different side effects. The most common ones include:

Skin changes

During EBRT treatment, radiation must pass through your skin. That can cause your skin to become red, swollen, warm, and sensitive, as if you have a sunburn. It may peel or become moist and tender. Depending on the dose of radiation you receive, you may notice hair loss or less sweat within the treated area.

These skin reactions are common and temporary. They'll fade gradually within four to six weeks after you finish your treatment. If you notice any skin changes outside the treated area, tell your doctor or nurse.

Long-term side effects, which can last up to a year or longer after treatment, may include:

  • A slight darkening of the skin
  • Enlarged pores
  • Either more or less skin sensitivity
  • A thickening of tissue or skin

To reduce skin reactions:

  • Gently cleanse the treated area using lukewarm water and a mild soap. Don't rub. Pat your skin dry with a soft towel, or use a hair dryer on a cool setting.
  • Try not to scratch or rub the treated area.
  • Don't put any ointment, cream, lotion, or powder on the treated area unless your radiation oncologist or nurse has prescribed it.
  • Don't wear tight-fitting clothing or irritating fabrics. Instead, choose clothes made from natural fibers, such as cotton.
  • Don't apply medical tape or bandages to the treated area.
  • Don't expose the treated area to extreme heat or cold. Avoid using an electric heating pad, hot water bottle, or ice pack.

It's very important not to expose the treated area to direct sunlight. That could intensify your skin reaction and lead to a serious sunburn.

With brachytherapy, you may have swelling, bruising, bleeding, or pain around the spot where you get treatment.

Tiredness

Everyone has different energy levels, so prostate radiation treatment will affect each person differently.

People often feel fatigued (tired) after several weeks of treatment. For most, this fatigue is mild, and you might be able to stick to your normal routine during treatment, including working full time. But some people lose a lot of energy and need to change their daily routine.

If your doctor thinks you should limit how active you are, they'll discuss it with you.

To minimize fatigue while you're receiving radiation treatment:

  • Get enough rest.
  • Eat well-balanced, nutritious meals.
  • Pace yourself, and plan rest breaks throughout your day.

Know that your fatigue might not lift until a few weeks or months after you finish getting radiation therapy.

Lymphedema

If radiation therapy damages the lymph nodes around your prostate gland, the fluid can build up in your legs or genital area. That can cause swelling and pain. Physical therapy can usually treat lymphedema, but it might not go away completely.

Bowel problems

Radiation can irritate your rectum and bring on a condition called radiation proctitis. You might get diarrhea, bloody stool, or have trouble controlling when you poop. Most of these side effects fade eventually. Your doctor may tell you to follow a special diet during treatment to minimize bowel trouble.

Nausea and vomiting aren't common unless you get radiation therapy on your upper belly area.

Urinary problems 

Radiation can irritate your bladder, which could lead to a condition called radiation cystitis. You might:

  • Have to pee more often
  • Feel like it burns when you pee
  • Notice blood in your urine

Such problems usually get better over time, but for some people, they don't go away.

There's also a chance you'll have trouble controlling your urine (pee), or it may leak or dribble. That's part of a condition called urinary incontinence. It's a side effect that happens less often with radiation than after surgery.

One rare side effect of radiation therapy for the prostate is that the tube that carries pee from your bladder out of your body, called the urethra, could become too narrow or close off. If that happens, you'll need more treatment to open it back up.

Erection problems 

These can include impotence, or trouble getting or maintaining an erection. If you get erection problems after radiation therapy, they usually develop slowly over time rather than right away. The older you are, the higher your chances for trouble getting erections. Your doctor can suggest treatments, including medicines, that can often help.

Keep these side effects in mind when you think about your treatment options. If you have any concerns, don't hesitate to speak up.

And while you're going through prostate radiation therapy, talk to your doctor about any side effects you have. Ask for ways to get relief.

Good nutrition is an important part of recovering from the side effects of radiation therapy.

When you eat well, you have the energy to do the activities you want to do, and your body is able to heal and fight infection. Most importantly, good nutrition can give you a sense of well-being.

Since it can be hard to eat when you don't feel well, let your treatment team know if you're having trouble. You could also consider working with a dietitian. They can help make sure that you're getting enough nutrition during your radiation therapy.

These tips might help while you're going through treatment:

Try new foods. Things that you haven't liked in the past may taste better to you during treatment.

Power up with plant-based foods. They can be healthy and tasty substitutes for meat. So, for instance, swap out a burger or chicken for beans and peas at a few meals each week.

Eat a rainbow of fruit and vegetables. Get your fill of these healthy powerhouses every day. Good options include spinach, raspberries, yellow peppers, carrots, and cauliflower.

Limit or avoid unhealthy choices. That includes red or processed meats, sugary foods and drinks, and processed foods.

Aim to stay at a healthy weight during treatment. You can ask your doctor what your ideal range on the scale should be. It's normal to have small weight changes while you go through treatment.

Try to stay physically active. If you're not active now, you can ask your doctor how to move more and exercise safely.

Can I travel after radiation therapy?

If you're feeling up to it, you should be able to travel after radiation therapy as long as your doctor is OK with it. Plan ahead for dealing with side effects like tiredness or bowel and bladder problems. If you had permanent brachytherapy, it's possible you could set off a radiation detector, so you might want to carry a note from your doctor.

Can you eat bananas during radiation?

Generally speaking, bananas are a smart choice during prostate radiation therapy. Their fiber and potassium can help control diarrhea. The exception would be if bananas give you gas. Having a gas bubble during a treatment could push your intestines into the path of the radiation.

Who can I contact if I have concerns about my treatment?

Many hospitals and clinics have a staff social worker who can help you during your treatment. Check with your doctor to see if this is available to you.

The social worker can discuss any emotional issues or other concerns about your treatment or your personal situation, and they can give you information about resources. They can also discuss housing or transportation needs if you need.

People dealing with certain medical issues find it helpful to share experiences with others in the same situation. Your doctor can give you a list of support groups if you're interested. Your social worker can offer more information about finding support, and you can look online for support group resources.

What about follow-up care?

After your radiation therapy sessions are complete, you'll visit your doctor for regular follow-up exams and tests. Your doctor will tell you how often to schedule your follow-up appointments.

You can also ask your doctor for a survivorship care plan. This outlines things such as:

  • The treatment you received
  • What side effects you may get in the short and long term
  • Who should be following you for testing and care