Radiation therapy for prostate cancer

By Dr. Ananya Mandal, MDReviewed by Sally Robertson, B.Sc.

Radiation therapy is widely used in many forms of cancer including prostate cancer. This therapy uses high energy waves to kill cancer cells.

Radiotherapy may be used to enhance the effects of chemotherapy or to shrink a localized tumor before it is surgically removed by radical prostatectomy. Radiation may also be used after prostatectomy to kill any remaining cancer cells or to relieve symptoms in people with advanced or recurring cancer.

Some examples of the types of radiation treatments available include:

External beam radiation therapy or EBRT

For this therapy, high-energy radiation beams generated by a machine are directed at the area of the body where the prostate gland is located. This type of therapy is usually delivered five times a week over the course of six or seven weeks. The treatment procedure is painless but some of the side effects include sore skin, nausea, vomiting, fatigue, hair loss and problems with eating and drinking.

Conformal radiation therapy

This procedure involves the use of a computer to direct the radiotherapy beams specifically to the prostate area. This minimizes the damage caused to adjacent normal tissue and causes less side effects than EBRT. The National Institute for Health and Clinical Excellence (NICE) now recommends the use of conformal radiotherapy as the optimal method for delivering external radiotherapy in prostate cancer.

Intensity modulated radiotherapy (IMRT)

IMRT is an advanced form of conformal radiotherapy that can harness the radiation beams even more precisely, delivering them directly to the tumor site and even at varying doses to different parts of the tumor. A machine moves around the patient and beams are angled to hit specific parts of the prostate at certain intensities while the dose that reaches the more healthy tissue is minimized.

The most modern machines have scanners inside them that provide images of the prostate that the doctor can use to adjust the aim of the beams before delivering the radiation. This is called image guided radiation therapy. This may reduce the side effects of treatment further still, although research to confirm this is ongoing.

Proton beam radiation therapy

Proton beam radiation therapy uses photon beams rather than X-rays. Proton beams release energy only after they reach the site they are directed at rather than releasing energy as they travel towards the target site, like X-rays do. This means proton beams can deliver radiation to the site of interest while avoiding damage to local healthy tissue. Proton beam radiation can be combined with CRT and IMRT to enhance aim.

Brachytherapy (internal radiation therapy)

Also called “seed therapy,” this procedure involves the implantation of radioactive pellets or “seeds” about the size of grains of rice into the prostate gland. Brachytherapy is generally used for early stage prostate cancers that are slow growing.

Brachytherapy may be given on a permanent basis at a low dose rate (LDR) or on a temporary basis at a high dose rate (HDR).

In permanent or LDR brachytherapy, seeds of iodine-125 or palladium-103 are inserted into the prostate using thin needles. The seeds remain in place and give off low doses of radiation for weeks or months. Around 40 to 100 seeds may be placed at a time.

Temporary or HDR brachytherapy involves the delivery of radioactive iridium-192 or cesium-137 using catheters over 5 to 15 minutes. Usually, around three sessions are scheduled over the course of two days and the catheters are removed after the last treatment.

Further Reading

• All Prostate Cancer Content
• Prostate Cancer
• The Prostate
• Prostate Cancer Risk Factors
• Prostate Cancer Screening