Radiation Therapy for Prostate Cancer

External Beam Radiation Therapy (EBRT)

A machine outside the body focuses beams of radiation on the prostate gland. This type can be used to try to cure early stage cancer. It may also help to ease problems such as bone pain if the cancer has spread.

Measurements will be taken before treatment. CT or MRI scans may be used to find the best angle and dose of radiation. A plastic mold of a person's body may also be made. It will help keep them in the same position for each treatment. This will make the radiation treatment more accurate.

EBRT is often given 5 days a week for several weeks. Each treatment is like getting an x-ray with stronger radiation. The procedure does not cause any pain and each treatment lasts only a few minutes. Setup time before treatment takes longer.

Types of EBRT include:

• 3D conformal radiation therapy (3D-CRT)—uses special computers to map the prostate. Radiation beams are then shaped and aimed at the prostate from several directions. This makes it less likely to damage normal tissue.
• Intensity modulated radiation therapy (IMRT)—an advanced form of 3D therapy. This is the most common type of EBRT for prostate cancer. The machine moves around the person as it delivers radiation. The beam is shaped, aimed as above. The strength of beam can also be changed. It will limit radiation of healthy tissue and increase radiation to cancer. IMRT can give large doses of radiation in each session. The treatment is given over just a few days.
• Stereotactic body radiation therapy (SBRT)—uses imaging to aim higher doses of radiation at the cancer. This can also mean a shorter treatment cycle because a person gets higher doses of radiation each time. Because larger doses of radiation are used a person may have worse side effects than other types of radiation therapy.
• Proton beam radiation therapy—focuses beams of protons instead of x-rays on the cancer. Protons cause little damage to the tissues they pass through. They also release their energy after traveling a certain distance. This means that proton beam radiation can deliver more radiation to the prostate. It can also cause less damage to nearby normal tissue. Proton beam radiation can be aimed like 3D-CRT and IMRT.

Brachytherapy

Seeds the size of a grain of rice are put in the prostate between the scrotum and anus. Higher doses of radiation can be used with this method. The seeds can be:

• Permanent—Low-dose seeds are placed that send out radiation. They can be used for a longer time. In some, it may be months.
• Temporary—A high-dose seed is sent into the body by tubes. Radiation is given for up to 15 minutes, then the seed is taken out. This may be given up to 3 times over the course of 2 days. The tubes stay in place until treatment is no longer needed.

Some people may need more than one type of brachytherapy.

Radiopharmaceutical Therapy

Alpha emitter radiation therapy is delivered to the cancer through an IV. It is used to kill cancer that has spread to the bones.

Side Effects and Management

Radiation aimed at the pelvis causes irritation. A person may have:

• Erectile dysfunction
• Blood in the stool
• Pain during bowel movements
• Diarrhea
• A harder time holding urine
• To pass urine more often
• Narrowing of the tube that carries urine out of the body from the bladder—this is rare

There are many ways to treat these problems. Other common issues are dry, sore skin, nausea, vomiting, and feeling tired because of anemia. Talk to the care team as soon as these symptoms start so they can be better controlled. The dose of radiation may need to be changed to help ease side effects.