Radiotherapy or radiation therapy is a prostate cancer treatment in which the patient is exposed to high doses of radiation (high-energy rays or particles) to kill the cancer cells and shrink the malignant tumor.

The radiation oncologist is specially trained to treat cancer with radiation. While giving radiation to the prostate, he makes sure that it causes as little harm as possible to the nearby healthy tissues.  These mainly include the bladder, rectum, and bowel.

In prostate cancer, radiotherapy is used:

  • As the first line of treatment for cancer that is still contained within the prostate gland and is of low grade. Success rates are comparable with and about the same as achieved with radical prostatectomy.
  • As part of the first line of treatment for prostate cancers that spread outside the prostate into the nearby tissues.
  • If there is a recurrence after surgery of the prostate
  • In cases of advanced prostate cancer, radiotherapy keeps cancer and its symptoms under control.

Types of prostate cancer radiotherapy

The main types of radiation therapy used for treating prostate cancer are:

  1. External beam radiotherapy is given from outside the body from a radiotherapy machine.
  2. Brachytherapy – radiotherapy is given from inside the body (internal radiation) using seeds that are implanted in the patient’s prostate

1. External beam radiotherapy (EBRT) for prostate cancer

EBRT is the most common type of radiation therapy used for cancer treatment. It is a local therapy meaning that it targets a specific part of the body and not the whole body.

In this type of radiotherapy for prostate cancer, beams of radiation from the radiation machine, called a linear accelerator (LINAC), target the prostate gland. The radiation comes from the machine outside the body and hence the name, “external”.

EBRT is specially used

  • for early cancer of the prostate
  • after surgery for prostate cancer
  • to manage cancer that has recurred or is at high risk of recurrence
  • in prostate cancer with metastasis (that has spread), to relieve symptoms such as bone pain

Radiation treatment is a painless procedure and is given 5 days a week on an outpatient basis for several weeks. The duration of the whole treatment depends on a case-to-case basis. Each session lasts a few minutes only.

Newer EBRT techniques are more focused and allow for higher doses of radiation to the tumor. Being highly focused, they minimize the radiation exposure to the nearby healthy tissues.

Radiotherapy does not make you radioactive. It is safe for you to mix with other people including children during this therapy.

Usually, side effects start appearing after the second or third week of treatment and they are local. They include urinary symptoms, bowel complaints, worsening of hemorrhoids, and fatigue. Side effects slowly improve and may last for two to six weeks after completion of radiotherapy.

Learn more about the recommendations for external beam radiation therapy for prostate cancer.

Success rate with EBRT

Prostate cancer radiotherapy provides excellent results and long-term disease control. Survival rates are comparable to those of other treatments, including surgery.

The success rate for men with localized prostate cancer that has not spread and treated with external-beam radiation therapy is promising and shows good results. It is

  • 95.5% for intermediate-risk prostate cancer and
  • 91.3% for high-risk prostate cancer

The 5-year survival rate with this treatment is 98.8% overall.


According to a study published in the Journal of the American Medical Association, 19.6% of those who were treated with high-dose radiation therapy experienced recurrence within five years.

Intensity-Modulated Radiation Therapy (IMRT)

This is a newer form of external beam radiation, which is delivered by linear accelerators. The oncologist can control and adjust the concentration and direction of the radiation beams, which enables him to better focus on the prostate and limit damage to the neighboring bladder and rectum.

IMRT enables the administration of more precise, intense, and effective doses of radiation to the prostate. Radiation is delivered to the patient using a computer-controlled device that moves over the patient.

Proton Beam Therapy

Proton therapy is a form of EBRT that is more used now because of its more focused approach. More and more specially equipped centers offer it. The radiation process has been modified from a passive scattering approach to scanning proton beam therapy.

Proton beam therapy emits proton beams instead of x-rays on cancer. Unlike x-rays, protons cause little damage to the tissues they focus on and release their energy only after going the required distance.

This allows the proton beam radiation to deliver more radiation to the prostate while causing little damage to the neighboring normal tissues. Proton beam radiation can be aimed with more precision similar to IMRT.

Current evidence suggests that it is comparable to other radiation methods in eliminating prostate cancer.

However, more studies are required to prove the superior efficacy of proton beam therapy over x-rays. Secondly, proton beam therapy is not widely available because the machines needed to make protons are very expensive, and their availability is very limited even in the United States. Thirdly, all insurance companies might not cover proton beam radiation expenses yet.

Possible EBRT side effects

EBRT side effects arise from the undesired effects of radiation on the healthy neighboring tissues of the prostate.

  • Bowel problems: Due to the irritation of the rectum by the radiation, you can develop diarrhea with blood in the stools along with rectal leakage. This is called radiation proctitis. With time this problem goes away. To lessen the symptoms, the doctor may put you on a diet that is high in fiber, which will soften the stools and improve your symptoms. You will be asked to avoid caffeine, fructose, and sugar alcohols.
  • Urinary problems: Radiation can irritate the urinary bladder and cause a condition called radiation cystitis. You may have a burning sensation while passing urine, the frequency of urine may increase and there may be blood in your urine. This problem goes away with time but in some men, it may persist.
  • Some men may develop urinary incontinence, which means they are not able to control their urine and this may lead to leakage of urine.
  • Urethral stricture another complication that may arise in which there is a narrowing of the urethra or even its blockage.
  • Erectile dysfunction (ED): With radiation, some men may develop impotence gradually over time. This complication also occurs with surgery but the onset is of a sudden nature. Treatment of ED with medication can help.
  • Fatigue: There is a general feeling of tiredness during radiotherapy. This feeling of fatigue may last for several weeks even after the treatment stops.
  • Lymphedema: Radiation can damage the lymph nodes around the prostate leading to the blockage of the lymphatic drainage. This can cause swelling and pain in the legs and genital area. Physical therapy can help but in some men, the problem may persist.

2. Brachytherapy (Internal radiation therapy)

In brachytherapy, small radioactive “seeds,” each about the size of a grain of rice are placed directly into your prostate. These pellets or seeds produce gamma-rays, which act in the same way as X-rays on the cancer cells. This treatment reduces the risk of damage to surrounding healthy tissue, thereby minimizing the side effects.

There are two main types of brachytherapy:

  1. Low dose rate (LDR) and
  2. High dose rate (HDR)

Brachytherapy may be used alone or in combination with external radiation for prostate cancer. Brachytherapy alone is generally used in cases with a slow-growing early-stage cancer

Brachytherapy combined with external radiation sometimes gives better results in men who are at a higher risk of cancer spreading outside the prostate (for example, if you have a higher Gleason score).

Brachytherapy is performed in the operation theater and the patient will have to stay overnight in the hospital. The patient is given either spinal or general anesthesia.

The radiation therapist uses imaging tests such as transrectal ultrasound, CT scans, or MRI to help him place the radioactive pellets in the right areas of the prostate. A special computer software program helps him to calculate and use the exact dose of radiation needed.

Permanent LDR brachytherapy

In permanent low dose brachytherapy, small radioactive ‘seeds’ or pellets are permanently implanted near or in the tumor. These pellets keep on releasing small amounts of radiation over several weeks or months.

The radiation from the seeds travels a very short distance, which minimizes the damage to nearby healthy tissues.

The pellets are placed inside thin needles, which are inserted into the prostate through the skin in the area between the scrotum and anus. The pellets are left in place as the needles are withdrawn.

The seeds are so small that they do not cause discomfort. Usually, about 100 seeds are placed inside the prostate and they are left in place permanently even after their radioactivity is used up.

Temporary HDR brachytherapy

High dose rate brachytherapy delivers a more intense dose of radiation, which is short-lived during each session of therapy. Usually, 1 to 3 sessions are given over two days.

The radioactive sources are removed after each session and not placed permanently as LDR brachytherapy. HDR is often used along with external beam radiation therapy (EBRT) in more high-risk but localized prostate cancers.

Side effects of brachytherapy

Side effects of brachytherapy are somewhat similar to those of EBRT and are due to radiation affecting the nearby healthy tissues of the prostate.

They include:

  • Bowel problems such as rectal pain, burning, and/or diarrhea (sometimes with bleeding) can occur due to radiation proctitis.
  • Urinary problems can include severe urinary incontinence (trouble controlling urine) and increased frequency of urination due to radiation cystitis.
  • Rarely, the urethral lumen may close (urethral stricture) and may need to be opened with a catheter or surgery.
  • Erection problems can occur with brachytherapy and to the same extent as EBRT  or surgery. The younger you are, the more likely you will be to regain function after treatment.
  • Radiation precautions are necessary in view of the fact that your prostate is carrying radioactive pellets. You will be advised to stay away from pregnant women and small children during this time as a precautionary measure.

Read ASCO’s recommendations for brachytherapy for prostate cancer

What to eat and what to avoid during radiotherapy for prostate cancer

  • Eat smaller meals more frequently.
  • Stay hydrated. Drink plenty of water throughout the day.
  • Focus on nutrient-dense foods like fruits, vegetables, whole grains, and lean proteins.
  • Whole grains include brown rice, whole-grain breads, and cereals
  • Lean proteins include protein-rich foods that are low in fat: Include seafood, lean meat and poultry, eggs, beans, soy products, and nuts and seeds without salt.
  • Fat-free or low-fat (1%) milk and milk products such as cheese and yogurt, provide calcium, potassium, and other nutrients. If you have a problem digesting dairy products, include soy, almond, or coconut milk without sugar.