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How is radiation therapy used to treat prostate cancer?

Radiation causes prostate cancer cells to die. It can be delivered in pellets placed directly in the prostate (called seeds or brachytherapy) or from outside the body (external beam therapy). There are many forms of external beam therapy using different agents (protons, electrons) and different ways of targeting the radiation at the prostate. Radiation can also be used in men whose cancer has spread to the bones to treat the cancer in the bones.

There are two main types of radiation therapy used to treat prostate cancer:

  • External beam: involves a computer aiming radioactive rays at your prostate from outside your body to kill cancer cells.
  • 3D conformal radiation therapy (3D-CRT): 3D-CRT uses special computers to precisely map the location of the prostate. This mapping makes it possible to aim the radiation treatment directly at the prostate, avoiding other structures.

Intensity Modulated Radiation Therapy (IMRT): an advanced form of 3D-CRT with the same three-dimensional mapping capability. IMRT uses a computerized machine that moves around you to deliver radiation beams from different angels. IMRT allows physicians to adjust the strength of each radiation beam to minimize the doses that reach more sensitive tissue. The placement of three gold markers within the prostate is required to indicate the precise location of the prostate before treatment begins.

Calypso 4D System: The Calypso 4D System uses radiofrequency waves that allow for very accurate alignment of your prostate for each treatment session. It monitors the position of the prostate at all times during radiation treatment delivery. Three tiny transponders are implanted in your prostate and are required to monitor the prostate in real time throughout your treatment. Calypso allows your physicians to monitor exactly where the prostate is at all times to make quick and important decisions about your care.

CyberKnife: Surgeons are now utilizing the CyberKnife radiosurgery system, a robotic arm that can provide large and precise doses of radiation to tumors and reduces the number of treatments needed from 40 over an eight-week period to five or so over a week. Placing fiducial markers accurately identifies the prostate. Similar to surgery, radiation treatment can cause impotence, though it may not occur right away after the surgery but rather over time.

  • Brachytherapy: involves implanting radioactive seeds in your prostate to kill cancer cells. This method of treatment may have fewer side effects.

Radiation therapy is used to treat prostate cancer. Most of the complications that arise from radiation usually involve the bladder and the rectum. Some of the radiation, despite the best technology, is going to go to the bladder and rectum, given the fact that the prostate is located between them. So a small percentage of patients may retain some of the side effects they may have experienced during treatment. For instance, there may be trouble with the bladder, such as urinary frequency, a burning sensation during urination, or a sense of urgency. Rectal symptoms may include frequency, urgency, looser stools or irregularity. In the vast majority of patients who undergo radiation treatment, side effects slowly subside over time, but there’s a small percentage of patients who experience chronic side effects from radiation therapy.

Radiation therapy is an alternative to surgery, and the risks of complications from radiation are less than from surgery. But radiation is also generally believed to be less likely to "cure" the cancer (in this case, to kill all the cancer cells) in suitable candidates. Death as a direct result of radiation is possible but very unlikely—only about 1 in 500 treated men die.

Gastrointestinal problems are quite common during treatment; pain, diarrhea or rectal urgency may occur in about 33 out of 100 cases. This usually improves when treatment is completed.

Erectile dysfunction (impotence) may result if the nerves responsible for erections are damaged during radiation. These nerves run directly over the surface of the prostate and, depending on the extent and location of the tumor, may be very difficult to avoid. About 25 to 40 out of 100 men are likely to suffer erectile problems after conventional external radiation.

Urinary problems may occur if radiation damages the urethra or the bladder. Mild incontinence may be expected in about 5 to 10 men out of every 100 who undergo prostate irradiation; complete incontinence occurs seldom (less than 1 out of 100). Bladder or rectal injuries are also possible but are uncommon. Urethral strictures may result from scar tissue formation. These cause the urethra to narrow and make urination difficult. About 5 out of every 100 men who go through radiation treatment require at least one procedure to dilate the urethra.

Brachytherapy treatment (inserting tiny radioactive "seeds" in the prostate) can cause difficulty passing urine that can last up to one month after treatment. Long-term issues can include continued difficulty passing urine. Two out of 100 men also experience proctitis, a chronic condition characterized by rectal straining and bleeding. Approximately 10 percent to 15 percent of men who receive brachytherapy become impotent.

Radiation therapy, also known as radiotherapy, involves the use of radiation to kill cancer cells and shrink tumors. Radiation therapy may be:

  • external radiation therapy—radiation directed at the tumor from a source outside the body;
  • internal radiation therapy—dozens of tiny radioactive seeds are implanted directly into the prostate gland using needles; the seeds remain in the prostate gland permanently; this method delivers directly to the affected area, and reduces the risk of damage to surrounding areas such as the rectum and bladder; internal radiation therapy is most often used for treating earlier stage cancers.

Radiation therapy is localized, so side effects are usually experienced only in the areas of the body where it is administered. Numerous side effects are a direct result of radiation; some are minor and diminish after therapy is stopped and can include fatigue, skin inflammation in the treated areas, frequent or uncomfortable urination and rectal bleeding or irritation. Some side effects, however, are permanent. Bowel function may never become normal even after treatment is stopped; impotence can occur up to 2 years post-treatment in some patients.

One of two radiation therapy treatments for prostate cancer, external beam radiation therapy, involves the use of computer imaging to map out the precise location of the cancer cells in order to target a high level of radiation only to that area. The treatment is painless and is given five days a week for about eight weeks. While the radiation is only given for about one minute, the appointments take 10 to 15 minutes because of the time it takes to set up the person so that the radiation hits the precise location of the cancer cells. In fact, a person undergoing this treatment will be given tiny tattoos to mark the spot where the radiation machinery should be placed. Each treatment appointment takes about 10 minutes. Side effects may include diarrhea, problems urinating, fatigue, and possibly sexual side effects.

Dr. Mark E. Chisam, MD
Radiation Oncologist

Radiation therapy may be used alone or combined with hormonal treatment to treat prostate cancer. It is most effective in treating cancers that have not spread outside the prostate.

External beam radiation therapy uses high energy radiation beams to destroy cancer cells. The radiation damages the DNA within the cancer of cells so that they can't grow and spread. Although radiation damages normal cells as well as cancer cells, the normal cells can repair themselves better and faster than cancer cells. External beam radiation therapy is also very effective when persistent cancer is detected with PSA measurements following surgery.

External-beam radiation therapy uses a large machine to precisely aim a beam of radiation at your tumor. The tumor is targeted with a special type of CT scan and multiple beams are individually designed for your tumor, minimizing any damage to nearby healthy tissue. These radiation treatments usually are done 5 days a week for up to 8 weeks, lasting about 30 minutes per day.

Dr. Marc B. Garnick, MD
Hematologist & Oncologist

Prostate cancer radiation therapy uses radiation to destroy cancerous cells and is a reasonable alternative to surgery. There are two ways to deliver radiation: by aiming an external beam of radiation at the tumor, or by surgically implanting small radioactive pellets in the prostate gland (an approach called brachytherapy). To improve survival, radiation therapy is sometimes used in combination with a form of hormone therapy and if the hormonal therapy is given before the radiation, it is known as neoadjuvant hormone therapy.

Any man with prostate cancer can elect to have radiation therapy. But prostate cancer cells can sometimes survive a full course of radiation, meaning that the disease may recur years later, when it can no longer be treated with radiation. (There is a limit to how much radiation one can have.) This is the main reason why urologists tend to recommend surgery for men with early-stage cancer who are age 60 or younger, and to recommend radiation therapy for men over age 70. Between these ages, the choice of treatment will hinge upon several factors, such as your general health, life expectancy, urinary and erectile function, lifestyle, and preferences, as well as the extent of your cancer. However, radiation oncologists often disagree with these age breakdowns, and improved techniques are leading many to challenge once widely held beliefs about age and radiation therapy.

Radiation therapy uses targeted energy to kill cancer cells, shrink tumors and provide relief of certain cancer-related symptoms. Radiation therapy is a preferred treatment option for prostate cancer patients. Highly targeted radiation treatments are used to kill tumors, along with other innovative therapies, like hormone therapy and immunotherapy, which fight against the growth of new cancer cells.

Radiation oncologists deliver high radiation doses to cancerous cells in the prostate, while sparing healthy tissue and organs. By focusing the radiation directly on the tumor, these therapies minimize the risk of developing radiation side effects commonly associated with prostate cancer treatment, like incontinence and erectile dysfunction.

Two primary types of radiation therapy are used for the treatment of prostate cancer:

  • External beam radiation therapy (EBRT): Delivers high doses of radiation to prostate cancer cells from outside the body, using a variety of machine-based technologies.
  • High dose rate (HDR) brachytherapy (internal radiation): Delivers high doses of radiation from implants placed close to, or inside, the tumor(s) in the body.

Prostate cancer is commonly treated with radiation therapy, which uses high-energy rays (similar to X-rays) to kill cancer cells. Radiation therapy is an option for early-stage prostate cancer and advanced prostate cancer. In addition, radiation therapy helps avoid surgery in patients who are too ill to risk having anesthesia, and is usually offered to older patients with early-stage prostate cancer due to fewer side effects.

Radiation therapy for prostate cancer can be given by using external beam radiation therapy, brachytherapy or photodynamic therapy.

Radiation therapy for prostate cancer can have impotence rates similar to surgery (urinary incontinence and impotence), but the risk of urinary incontinence is very low. Impotence may develop months to years after the radiation treatment, unlike with surgery, which tends to have the side effects occur immediately. Other side effects from radiation include proctitis (inflammation of the rectum), cystitis (inflammation of the bladder) and fatigue.

Your radiation oncologist tries to limit the amount of radiation to other organs in order to minimize these side effects.

Usually symptoms go away after treatment. However, in some cases, they may persist after treatment has ended.

Radiation therapy is a very effective treatment option for prostate cancer that is still confined to the prostate. Recent data support radiation therapy to the prostate as having similar outcomes as prostatectomy (surgery) for prostate-confined cancer, even going out 15 years from the time of treatment. Whether radiation is the optimal choice for a patient is determined by many factors, such as age of the patient, other health issues of the patient and preference of the patient. This is not a straightforward question, and patients need to sit down with their physicians to have a lengthy discussion regarding all their options, and then make a decision that is right for them.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.