Radiation therapy can be an effective treatment for prostate cancer. It can shrink a tumor, relieve symptoms, and delay or halt the growth of cancer cells.

A therapist may target a tumor with an intense beam of radiation from an external machine, or they may implant or inject radioactive materials into the body.

Radiation treatment has benefits but can also have risks and side effects. A doctor will be able to discuss the possible side effects with a person before they begin treatment.

This article reviews what radiation therapy means for someone undergoing prostate cancer treatment.

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The radiation particles damage the DNA in cancer cells. This disruption stops the cells from multiplying and can also kill them. Though some may die right away, cancer cells treated with radiation may die for days to months following the therapy.

In less advanced cases of cancer, radiation may remove all traces of cancer and may be a curative treatment. A doctor may use radiation alone or alongside other treatments.

If it is not possible to eliminate prostate cancer completely, radiation therapy can help control it.

It may also help relieve symptoms in the later stages of the disease when it is called metastatic prostate cancer. Doctors then refer to this as palliative treatment.

Prostate cancer is a common type of cancer that affects males. Learn more here.

A note about sex and gender

Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.

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Several types of radiation treatment are possible for prostate cancer.

These include:

  • external beam radiation
  • brachytherapy
  • systemic radiation (radiopharmaceuticals)

External beam radiation

In external beam radiation therapy (EBRT), a large machine will direct X-ray beams onto the prostate gland from outside of the body.

The medical team will prepare for the therapy by:

  • taking measurements and marking the treatment area
  • using MRI or CT scans to identify the target area
  • calculating the correct dose to use

Treatment typically involves 5 sessions a week for several weeks.

There are several ways to deliver EBRT:

  • Conventional therapy: With conventional therapy, a person receives a dose once a day, Monday through Friday, for about 7-9 weeks for a total of about 35–45 doses.
  • Moderate hypofraction: Moderate hypofraction uses a higher dose, which means a person may only have to attend 20 sessions over 4 weeks for the same benefit as conventional therapy spread out over 8-9 weeks.
  • Ultra-hypofraction: Ultra-hypofraction, also known as stereotactic body radiation therapy (SBRT) or colloquially as cyberknife, involves using 5 high doses of radiation over five sessions. For some people, this can mean more rapid treatment with fewer side effects and the same effectiveness as lower doses over several weeks. Not everyone is a good candidate, so a person should ask their doctor about this form of radiation.
  • Three-dimensional conformal radiation therapy (3D–CRT): 3D-CRT uses special computers to provide an exact image of the prostate gland. The computers then shape the beams so that they only affect the area that needs treatment and then fire the radiation from different angles. This can reduce the risk of damaging surrounding tissue.
  • Intensity-modulated radiation therapy (IMRT): In this more advanced version of 3D–CRT, a computer-driven machine moves around the person during treatment. It adjusts both the shape of the beams and their intensity. This makes it possible to deliver a higher dose without increasing the risk to healthy tissues.
  • Volumetric modulated arc therapy (VMAT): This version of IMRT delivers treatment rapidly so that each session is shorter. It is unclear whether it has additional benefits besides saving time.
  • Proton beam radiation therapy: Proton therapy delivers beams of protons instead of radiation. In theory, it causes less damage to healthy tissues because the radiation releases after it has passed through the surrounding tissue. However, this treatment is expensive and not widely available. It is not yet clear whether it is more effective than radiation therapy.

Brachytherapy or internal radiation therapy

Internal radiation therapy (IRT), also known as brachytherapy, involves placing radioactive seeds on the prostate gland inside the body. The seeds are around the size of a grain of rice.

The implant may be temporary or permanent:

  • Temporary: The doctor inserts the seeds into a small tube and leaves them there for between 5-15 minutes. A person may need 1-4 sessions, typically over the course of 2 days.
  • Permanent: The doctor will place around 1000 radioactive seeds that release radiation for several weeks to months. Often, they leave the seeds in place when not active since they likely will not cause discomfort.

Before inserting the seeds, the doctor will give the patient either a general or local anesthetic. They may use imaging technology to help ensure they position the seeds accurately.

Systemic radiation

In systematic radiation therapy, a doctor gives the person a liquid composed of radioactive substances, either by an injection or intravenously (IV drip). The medication, lutetium Lu 177 (Lutathera), will move around the body and attach to the prostate using what’s known as the prostate-specific membrane antigen.

If a person does not have this specific antigen, the medication will not work. A person will typically need 6 doses spread out over 6 weeks.

Treatment combinations

Sometimes, a doctor will recommend more than one type of radiation therapy. They may combine internal and external radiation therapy or change the method if one approach has not been effective.

Another option is to combine radiation therapy and chemotherapy. Chemotherapy can make cancer cells more receptive to radiation. Combining the two may lead to better results but can also lead to additional side effects. However, this combination is not a common choice.

Learn more about chemotherapy.

Radiation and anti-hormone treatment

These days, it is standard for doctors to combine radiation with androgen deprivation therapy (ADT), particularly for cancer that has progressed outside of the prostate.

Testosterone is a naturally present androgen, or hormone, in the male body. However, in some cases, it can cause prostate cancer to progress. Adding hormonal therapy to radiation can reduce the level of testosterone, which can help delay cancer progression.

However, a doctor will need to decide whether the benefit of adding anti-hormone therapy outweighs the potential side effects. This is because this type of therapy is effectively what is known as “chemical castration.” It may cause side effects such as:

  • Reduced libido
  • shrinkage of the testicles and penis
  • Erectile dysfunction (ED)
  • bone thinning
  • muscle mass loss
  • weight gain
  • hot flashes
  • higher cholesterol
  • depression

There are additional medications that a doctor may prescribe to help reduce some of these side effects. For example, certain anti-depressants can help reduce hot flashes and treat depression. There are also drugs to help treat osteoporosis.

A person can also use lifestyle factors to help with some of the effects such as exercising and eating a balanced diet.

Surgery may help in the early stages when cancer has not spread beyond the prostate. The risks often exceed the benefits if it has spread to other tissues.

Sometimes, a doctor will recommend both radiation therapy and surgery. Radiation may help shrink the cancer tumor before surgery or help prevent it from recurring following surgery.

In the early stages, radiation therapy may be just as effective as surgery, which may make it a better option for some people.

What does surgery for prostate cancer involve? Find out here.

Other options

Other treatment options include high intensity focus ultrasound (HIFU) and hormone treatments.

A person may also find that they qualify for a clinical trial. Clinical trials provide treatments using new medications or therapies, but not everyone qualifies.

A person interested should consider talking with their doctor about the possibility of joining a trial if they are interested.

Learn more about the stages of prostate cancer and the outlook.

Radiation therapy can cause some adverse effects, including:

Damage to healthy cells

Radiation therapy kills cancer cells, but it can also damage healthy cells.

However, unlike cancer cells, healthy cells can often repair themselves after treatment. This means that most of the adverse effects will be short-term. They will go away after treatment finishes.

Bowel and bladder problems

Radiation therapy for prostate cancer can irritate the bowel, the bladder, or both.

A person can develop:

  • Radiation proctitis. The symptoms include diarrhea and blood in the stool.
  • radiation cystitis. The symptoms include a need to urinate more often, a burning sensation when urinating, and blood in the urine.

Bladder problems may improve after treatment, but they may not go away completely.

Erectile dysfunction

Problems with achieving an erection may not appear at once, but they can develop over time, especially in older people. Medication may help.

Radiation may cause a slower loss of erectile function following treatment compared to surgery. About 70% of males who have erectile function at the beginning of treatment will still have it at the end. Moreover, radiation tends to have less impact in this area in the 5-10 years after treatment.

However, people who also receive ADT with radiation for 18-36 months or longer may lose more erectile function than those who do not.

Fifteen years post radiation treatment, the rate of people who experience ED is similar to people who have had surgery as a treatment.

With surgery, the negative impact on erectile function is more immediate. On the other hand, a person may recover function sooner.


Damage to the lymph nodes can cause fluid to build up over time in the genital area or the legs. This is known as lymphedema. An individual may notice swelling and pain. Symptoms may improve after treatment finishes, but they might not go away completely.

Other effects

Radiation therapy can cause a person to feel generally unwell.

They may experience:

  • skin soreness and sensitivity
  • physical fatigue
  • nausea
  • a loss of appetite
  • a sore or dry mouth

Rest can help conserve energy and ensure that the body and mind can continue with the course of treatment.

Cancer and its treatment can be emotionally draining. A doctor may be able to recommend a counselor who can help.

High doses of radiation can lead to long-term, irreversible side effects. In some cases, radiation may lead to another type of cancer later on, though the risk is relatively low. A person’s doctor should consider this possibility when they recommend treatment options.

If prostate cancer returns after a person has previously had radiation therapy, the doctor may not recommend it again. Doing so may expose the body to more radiation than it can safely withstand.

A person who has internal radiation treatment may give off a small amount of radioactivity afterward. The doctor may recommend staying away from pregnant people and young children during and following treatment.

Pregnancy and fertility

Doctors do not advise having radiation therapy during pregnancy, as it may harm the fetus. Anyone who becomes pregnant during treatment should tell their doctor as soon as they find out

Experts also advise that male patients still young enough to have children should consider alternatives to radiation because radiation can also negatively affect sperm. A person can also consider banking their sperm before treatment.

A person should discuss whether they are a good candidate for radiation therapy with their doctor.

However, some groups of people with prostate cancer may benefit more than others. They can include, but are not limited to, the following:

  • as an early treatment to cure or shrink the cancer
  • prevent cancer from coming back
  • to alleviate symptoms associated with advanced stages of prostate cancer
  • as a treatment for recurrent cancer (cancer that has come back)

A doctor administers prostate cancer treatment in an outpatient facility or hospital setting. A person will typically need several sessions of radiation spread out over several days each week for several weeks.

The exact process will vary based on the type of radiation a person receives, a person’s recommended dose, and how the doctor decides to proceed. The following is a general breakdown:

External beam radiation

For external beam radiation, a technician or computer aims the radiation directly at the area needed, in this case, the prostate. A person can expect to need between 5-45 sessions based on the exact type of external beam radiation they get.

These sessions typically occur several days each week and last for several weeks. A person will need to drive to the facility for treatment but will not likely have any downtime or need any special preparation.

Brachytherapy or internal radiation therapy

A doctor will place radioactive seeds into the prostate with a small tube or catheter during this procedure.

They will keep them in place for about 5-15 minutes when using temporary seeds. A person will typically need between 1 and 4 sessions with this method.

A doctor will place around 1000 seeds into the prostate for permanent or long-term seeds. These will give off radiation for several weeks to months and will remain in place following their effective period.

Systemic radiation

Systemic radiation involves radioactive medication that a doctor typically administers through an injection or intravenously. The medication, lutetium Lu 177 (Lutathera), attaches to the prostate to deliver radiation to cancer. A person will typically need 6 doses spread out once a week for 6 weeks.

A person should let their doctor know if they have side effects from the radiation treatment. They may have recommendations on how to cope with them.

Some possible suggestions for handling side effects include:

  • increase fluids and lean protein to help prevent dehydration
  • eat more soluble fiber, such as rice and potatoes, to help prevent diarrhea
  • maintain physical activity to help prevent fatigue
  • use topical creams and moisturizers on the skin and avoid soaps with a lot of chemicals

Radiation does not typically cause a need for downtime following a dose. However, it may cause a person to experience side effects that can affect their daily life, which can include:

  • fatigue
  • urinary or bowel incontinence
  • erectile dysfunction
  • nausea
  • soreness to skin

A person may find that maintaining a healthy diet and regular activity can help with a number of side effects. They may also benefit from maintaining a skin routine that involves the use of moisturizers and creams to help the skin heal.

The following sections provide answers to frequently asked questions about radiation for prostate cancer.

What is the success rate of radiation therapy for prostate cancer?

The success rate can depend on many factors, including a person’s overall health and the stage of cancer. Radiation therapy has around a 90% success rate in the early stages. The success rate may decrease with more advanced stages.

How long does it take for radiation to kill prostate cancer cells?

Radiation does not always work immediately. Instead, it can take several days to several months before cancer cells die off.

What are the chances of prostate cancer returning after radiation?

Most people will not have a recurrence following their initial treatment. However, about 25-33% of people who undergo surgery or radiation will have prostate cancer recurrence.

A doctor will only recommend radiation treatment for prostate cancer if they believe the benefits outweigh any risks and side effects.

Anyone with prostate cancer should speak with their doctor about the available treatment options and the possible adverse effects. The individual should decide with their doctor the best treatment course for them.