Aid & Information
Radiation treatment for prostate cancer requires accuracy and precision. With today's advanced radiation therapy systems, oncologists are better able to target difficult-to-reach tumors in the prostate. It can also direct higher radiation doses at prostate cancer cells, while reducing exposure to normal, healthy tissue.
Two main types of radiation therapy can be used: external beam radiation and brachytherapy (internal radiation). Both appear to be good methods of treating prostate cancer, although there is more long-term information about the results of treatment with external beam radiation.
Three-dimensional (3D) conformal radiation therapy is a technique where the beams of radiation used in treatment are shaped to match the tumor. Previously, radiation treatment matched the height and width of the tumor, meaning that healthy tissue was exposed to the beams. Advances in imaging technology have made it possible to locate and treat the tumor more precisely. Conformal radiation therapy uses the targeting information to focus precisely on the tumor, while avoiding the healthy surrounding tissue. This exact targeting makes it possible to use higher levels of radiation in treatment, which are more effective in shrinking and killing tumors. Three-dimensional conformal therapy is, in many ways, similar to intensity-modulated radiation therapy (IMRT); both are used to target cancer while sparing healthy tissue.
IMRT uses multiple small radiation beams of varying intensities to precisely radiate a tumor. The radiation intensity of each beam is controlled, and the beam shape changes throughout each treatment. The goal of IMRT is to bend the radiation dose to avoid or reduce exposure of healthy tissue and limit the side effects of treatment.
IMRT often requires multiple or fractionated treatment sessions. Several factors come into play when determining the total number of IMRT sessions and radiation dose. The oncologist considers the type, location and size of the malignant tumor, doses to critical normal structures, as well as the patient's health. Typically, patients are scheduled for IMRT sessions five days a week for five to eight weeks. At the beginning of the treatment session, the therapist positions the patient on the treatment table, guided by the marks on the skin defining the treatment area. If molded devices were made, they will be used to help the patient maintain the proper position. The patient may be repositioned during the procedure. Imaging systems on the treatment machine such as x-ray or CT may be used to check positioning and marker location. Treatment sessions usually take between 10 and 30 minutes.
The use of Stereotactic Body Radiation Therapy (SBRT) is quickly expanding due to significant advances in radiation therapy along with a history of success. SBRT requires higher doses and fewer treatments making accurate patient positioning even more important. This requires a 4-dimensional imaging, such as computed tomography (CT), that accounts for motion. These images are used to create customized treatment plans that direct several radiation beams of different intensities at different angles precisely to the tumor.
Radiation oncologists work with medical physicists to develop a radiation plan that ensures safe exposure to normal structures. Each of the treatment sessions takes 30 to 60 minutes and, unlike with more invasive therapies, the patient leaves each treatment free of significant pain or side effects. Treatments do not have to be administered on consecutive days, but the entire course of therapy is usually concluded within 10 days.
RapidArc® radiation therapy is a new technique that combines the sophistication of intensity modulated radiation therapy (IMRT) with dynamic arc based therapy. The combination of these two techniques has resulted in improvements in the precision and speed with which advanced treatments are delivered. RapidArc® is a volumetric arc therapy that delivers precise, three-dimensional treatment with a single 360-degree rotation of the linear accelerator gantry. This is possible because the treatment algorithm simultaneously changes the rotation speed of the gantry, the shape of the treatment field, and the delivery dose rate. Treatment is delivered to the whole tumor rather than slice by slice. This combination allows treatments to be two to eight times faster than standard IMRT.
Treatment only takes about 90 seconds and is administered 5 days a week for up to 9 weeks
Proton therapy is an advanced type of radiation treatment that uses a beam of protons to deliver radiation directly to the tumor, destroying cancer cells while sparing healthy tissues. Protons enter the body with a low radiation dose, matches the tumors shape and volume or depth, and deposit the bulk of their cancer-fighting energy right at the tumor. Most patients tolerate the treatments extremely well and are able to continue to work, exercise and remain sexually activity during their treatment course and immediately after treatment is complete.
With proton therapy for prostate cancer, treatments typically take only 15 to 20 minutes each day and are delivered five days a week for approximately eight weeks.
Side effects of radiation therapy include itchiness or discomfort in the perineal skin (or the skin between the anus and scrotum); darkening of the skin in the anal area; abdominal discomfort, diarrhea, and excessive gas and cramping; fatigue; and loss of pubic hair. Bowel problems: Radiation can irritate the large intestine and rectum and lead to a condition called radiation proctitis. This can lead to diarrhea, sometimes with blood in the stool, and rectal leakage. Most of these problems go away over time, but in rare cases normal bowel function does not return after treatment ends. In the past, about 10% to 20% of men reported bowel problems after EBRT, but the newer conformal radiation techniques may be less likely to cause these problems.
Radiation can irritate the bladder and lead to a condition called radiation cystitis. You might need to urinate more often, have a burning sensation while you urinate, and/or find blood in your urine. Bladder problems usually improve over time, but in some men they never go away. About 1 man out of 3 continues to need to urinate more often.
Urinary incontinence is less common than after surgery. The risk is low at first, but it goes up each year for several years after treatment.
Erection problems, including impotence: After a few years, the impotence rate after radiation is about the same as that after surgery. It usually does not occur right after radiation therapy but slowly develops over a year or more. This is different from surgery, where impotence occurs immediately and may improve over time.
In older studies, about 3 out of 4 men were impotent within 5 years of having EBRT, but some of these men had erection problems before treatment. About half of men who had normal erections before treatment became impotent at 5 years. It's not clear if these numbers will apply to newer forms of radiation as well. As with surgery, the older you are, the more likely it is you will have problems with erections.
There are two types of brachytherapy that are used in the treatment of prostate cancer, permanent low dose radiation (LDR) and temporary high dose radiation (HDR). LDR brachytherapy uses iodine-125 and palladium-103 stored in titanium cases usually referred to as brachytherapy seeds. The seeds are permanently left inside the prostate gland and over the course of their radioactive lives, the seeds will continuously emit low levels of radiation.
HDR brachytherapy uses a single radioactive seed made of iridium-194 which is sometimes referred to as an iridium wire. Soft flexible plastic catheters are inserted through the perineum and into the prostate gland. HDR brachytherapy requires an overnight stay in the hospital during which a patient undergoes two or three treatments with the wire through each catheter.