Radiation Therapy for Prostate Cancer

Radiation therapy uses energy to attack prostate cancer cells. It can sometimes cure early-stage prostate cancer, sparing patients a prostatectomy. Additionally, patients may receive radiation after surgery to prevent the cancer from recurring. It’s often delivered over multiple treatment sessions.

Patients can be anxious at the prospect of receiving radiation. However, as a prostate cancer patient at Siteman, you can take comfort in knowing that your radiation oncology team is affiliated with the internationally recognized Mallinckrodt Institute of Radiology. Our radiation oncology specialists are leaders in tailoring radiation therapy to each patient’s needs. Our physicians use innovative, high-tech methods to target the tumor while protecting surrounding tissues. They also work to limit the number of radiation sessions, meaning that they achieve optimum results while reducing the treatment burden on their patients.

Radiation techniques available at Siteman include:

  • External beam radiation
  • Brachytherapy
  • Proton beam therapy
  • Radium-223

External-beam radiation therapy

External-beam radiation therapy treats prostate cancer with X-ray beams. The treatment is painless and only lasts for a few minutes at a time.

Washington University radiation oncologists at Siteman were among the first in the U.S. to deliver external-beam radiation using intensity-modulated radiation therapy (IMRT). This technique enhances the delivery of high doses of radiation. In addition, they also use advanced-imaging methods such as MRI and PET scans – a technique known as adaptive radiation therapy (ART) – to focus treatment on the prostate. In turn, this reduces radiation exposure to the adjacent bladder and rectum.

For patients whose cancer comes back after prior radical prostate surgery, radiation therapy can be an effective treatment. If the patient has had a prostatectomy, radiation targets the space where the prostate used to be.


Brachytherapy is a therapy in which a radioactive source is implanted within the body. There are two different types of brachytherapy: low-dose-rate and high-dose-rate.

Low-dose-rate brachytherapy

In low-dose-rate brachytherapy, the radiation oncologist places a number of tiny radioactive seeds in the prostate. These seeds emit a steady dose of radiation for several weeks, and then remain permanently – and harmlessly – in place. Siteman was the first medical center in the region to perform radioactive seed implantation for prostate cancer.

High-dose-rate brachytherapy

High-dose brachytherapy (HDR) involves temporarily placing a single radioactive source in the prostate using catheters. The radiation oncologist carefully controls the time and position of the radioactive source to maximize the radiation dose to the prostate and minimize the dose to the urethra, rectum and bladder.

Typically, the radiation oncologist inserts the catheters in the morning in the operating room under general anesthesia, then a CT scan is obtained for treatment planning, and the five-to-15 minute treatment takes place in the afternoon. A combination of a long-acting local anesthetic and other medications keep the patient comfortable until treatment delivery. Finally, the radiation oncologist removes the catheters at the end of the treatment. Patients go home that same day and are not radioactive.

HDR brachytherapy alone can be used to treat low-risk patients. It can also serve as a boost for higher-risk patients receiving external beam radiotherapy.  HDR brachytherapy can be used to treat failures from LDR brachytherapy or external-beam radiotherapy in select patients.

Siteman is the first and only medical center in the region to perform HDR brachytherapy for prostate cancer. More than 200 patients have received the treatment since our program opened in 2014.

Proton beam therapy

Proton beam therapy kills cancer cells with protons instead of X-ray beams. The main advantage of this treatment is that the proton beam can be adjusted to specific depths, which means that the beam can stop at its target instead of passing through the entire body.

Doctors may use proton therapy alone or in combination with other radiation therapies and/or hormone therapy.  Your doctor can determine if you are an appropriate candidate for proton therapy and if you are eligible for any clinical trials.

ThS. Lee Kling Proton Therapy Center at the Siteman Cancer Center is the only proton therapy center located in Missouri and the surrounding region. It houses the world’s first compact proton beam accelerator. Radiation oncologists and physicists here helped evaluate the system and developed the patient protocols as well as the quality standards for this advanced technology.

How does radium-223 treat prostate cancer?

Radium-223 is a radioactive isotope that radiation oncologists can administer through an IV. It can treat prostate cancer that has spread to the bones.

Physicians and researchers at Siteman are investigating other uses for radioactive isotopes in prostate cancer treatment. In particular, they hope to develop isotope treatments for metastatic prostate cancer that is not confined to the bone.