Radiation therapy is delivered via external beams or radioactive implants:
External-beam radiation therapy (EBRT)
External beam radiation treatment makes use of high-powered X-rays to kill cancer cells, using a machine to deliver the radiation beam. This type of radiation is effective at destroying cancerous cells, but it can also scar adjacent healthy tissue.
The first step in radiation therapy is to map the precise area of your body that needs to receive radiation. Doctors often use three-dimensional scans to determine the exact location of your prostate and surrounding structures. Computer-imaging software gives the radiation oncologist the ability to find the best angles to aim the beams of radiation. By using new techniques — which allow for more precise focusing of the radiation beams with concentration of the radiation dose to the targeted area — greater doses of radiation can be administered to your prostate without harming surrounding tissue.
A body supporter holds you in the same position for each treatment. You'll also be asked to arrive for therapy with a full bladder. This will push most of your bladder out of the path of the radiation beam. Ink marks on your skin help to guide the radiation beam, and small gold markers may be placed in your prostate to ensure the radiation hits the same targets each time. Custom-designed shields help protect nearby normal tissue, such as your bladder, erectile tissues, anus, and rectal wall.
Treatments are generally given five days a week for 8 weeks. Each treatment appointment takes about 10 minutes. However, much of this is preparation time — radiation is received for only about one minute. You don't need anesthesia with external-beam radiation because the treatment isn't painful.
While most men experience mild side effects from this type of treatment, nearly all of these side effects disappear shortly after treatment is completed. Most men don't have problems with erections or intercourse immediately after radiation therapy. However, radiation can cause sexual side effects in some men later in life. Most of these men respond to medications used for ED. The younger you are, the better your chance of retaining normal sexual function.
During treatment some men experience urinary problems. The most common signs and symptoms are urgency to urinate and frequent urination. These problems usually are temporary and gradually diminish in a few weeks after completing treatment. Long-term problems are uncommon.
Rectal problems — including loose stools, rectal bleeding, discomfort during bowel movements and a sense that you have to have a bowel movement (rectal urgency) — may arise during treatment. Once the treatment course is completed these problems generally subside. However, a few men may continue to experience rectal problems months after treatment, but these improve on their own in most men. Most long-term rectal symptoms are controlled with medications. Rarely, people develop persistent bleeding or a rectal ulcer after radiation. Surgery may be necessary to alleviate these problems.
Radioactive seed implants (Brachytherapy)
Radioactive seeds implanted into the prostate have gained popularity in recent years as a treatment for prostate cancer. The implants, also known as brachytherapy, deliver a higher dose of radiation than do external beams, but over a substantially longer period of time.
During the implant procedure - which typically lasts about one to two hours, performed under general anesthesia on an outpatient basis - between 40 and 100 rice-sized radioactive seeds are placed in your prostate through ultrasound-guided needles. The exact number of seeds inserted depends on the size of your prostate. The therapy is generally used in men with smaller or moderate-sized prostates, with small and lower-grade cancers. Sometimes, hormone therapy is used for a few months to shrink the size of the prostate before seeds are implanted.
The seeds may contain one of several radioactive isotopes - including iodine and palladium. These seeds don't have to be removed after they stop emitting radiation.
Iodine and palladium seeds generally emit radiation that extends only a few millimeters beyond their location. This type of radiation isn't likely to escape your body in significant doses. However, doctors recommend that for the first few months you stay at least six feet away from children and pregnant women, who are especially sensitive to radiation. All radiation inside the pellets is generally exhausted within a year.
Side effects of seed implants are somewhat different from that of external-beam radiation. Seed implants deliver a higher dose of radiation to your urethra, causing urinary signs and symptoms such as frequent, slower and painful urination to occur in nearly all men. You may require medication to treat these signs and symptoms, and some men require medications or the use of intermittent self-catheterization to help them urinate.
Urinary symptoms tend to be more severe and longer lasting with seed implants than with external-beam radiation. Rectal symptoms, however, may be less frequent and less severe. Some men experience impotence due to radioactive seed implants.
Unfortunately, both of these methods of radiation delivery do not allow final pathological evaluation. Furthermore, the PSA level after treatment continues to be detectable and makes assessment for disease recurrence difficult. Generally, three consecutive PSA rises are needed to diagnose cancer recurrence which to some, cause anxiety during future evaluation.