Radiation Therapy

Radiation Therapy uses high-energy rays to kill prostate cancer cells, shrink tumors, or prevent cancer cells from dividing and spreading.

Radiation doses are usually small and spread out over time. This allows the healthy cells to recover and survive, while the cancer cells eventually die. Radiation therapy is usually used when prostate cancer has not spread beyond the prostate. It can help prevent the cancer from spreading further.

Like surgery, radiation therapy works best when the cancer is located in a small area. In early stages of prostate cancer, radiation therapy may cure the disease. It may be used alone or in combination with hormone therapy when cancer cells have spread beyond the prostate to the pelvic area and for pain relief in prostate cancer that is no longer responding to hormone therapy and has spread to the bones.

Radiation therapy can be given either via external beams or with a type of internal radiation called brachytherapy. These types of radiation therapy are discussed below.

External Beam Radiation Therapy

In external beam radiation therapy, the rays are delivered by a machine, and the radiation is given in brief sessions, usually one session each weekday for several weeks. Many patients compare the treatments to having an x-ray. The procedure is painless and lasts for just a few minutes. External beam radiation therapy may be given alone or in combination with hormone therapy.

Recent advancements in external beam radiation therapy have led to two new methods of treatment: three-dimensional conformal radiation therapy and conformal proton beam radiation therapy. These developments may help reduce the side effects of external beam radiation therapy and increase treatment success. Newer treatments are often considered experimental until they can be shown to have the same success rate as more standard forms of therapy, and they may not be available at all radiation centers.

The Calypso System: GPS For the Body

The normal motion of the body’s internal organs presents challenges in delivering precise radiation therapy to small targets. Organs naturally move during radiation treatment. In treating prostate cancer, it is important that all the necessary radiation gets to the tumor and all possible precautions available are taken to avoid unnecessary radiation to healthy tissues surrounding the bladder and rectum. The Calypso 4D Localization System, referred to as GPS for the Body, is a breakthrough technology providing doctors with a way to precisely set up prostate radiation therapy and then monitor the prostate’s position during treatment.

The Calypso System uses tiny electromagnetic transponders, which are implanted into the prostate in an outpatient procedure prior to treatment. These beacon transponders emit radiofrequency waves which allow very accurate alignment of the prostate before each treatment session. It also lets doctors monitor the position of the prostate in real time during treatment delivery.

Three-dimensional Conformal Radiation Therapy (3D-CRT)

In three-dimensional conformal radiation therapy, high-tech computers are used to identify the location of the cancer inside the prostate gland.

The next step is the creation of a special protection device that the patient wears during the treatments. This device is similar to a body cast, but it is molded out of styrofoam and helps to keep the body still during treatment while the radiation is aimed at the cancer. When the patient wears the plastic mold during the treatments, the radiation beams can be aimed more accurately to target the prostate gland. The idea is to direct a high dose of radiation only toward the cancer cells, while reducing the amount of radiation that the surrounding noncancerous areas receive. If the healthy tissue can be spared from the effects of radiation, the patient will experience fewer side effects.

Conformal Proton Beam Radiation Therapy

Conformal proton beam radiation therapy is another new type of radiation therapy. This technique is similar to three-dimensional conformal radiation therapy, except that it uses protons to produce the radiation beam. Protons are microscopic particles that produce energy in the form of a radiation beam. The proton beams can pass through healthy tissue without damaging it, yet can still be aimed at cancerous tissue to destroy cells.

Advantages:

Major surgery usually can be avoided by using radiation therapy. Radiation therapy may cure prostate cancer in its early stages and may help extend life in later stages. It rarely causes loss of urinary control, and other side effects like impotence occur less often than with surgery. The newer techniques mentioned above look promising in terms of reducing the chance of adverse effects and increasing the chance of success.

Disadvantages:

Radiation therapy can cause a variety of side effects because healthy cells are often damaged along with the targeted cancer cells. Most of these are minor and disappear after therapy stops.

These side effects include:

  • tiredness
  • skin reactions in the treated areas
  • frequent and painful urination
  • upset stomach
  • diarrhea
  • rectal irritation or bleeding

There is also a chance of some permanent side effects, including impaired bowel function and impotence.

Prostate Brachytherapy(also called prostate seed implants)

In prostate brachytherapy, the rays come from tiny, radioactive seeds inserted directly into the prostate.

Brachytherapy may be used by itself or in combination with external radiation therapy. The seeds are too small to be felt by the patient and do not cause any discomfort. They are inserted into the cancer during a surgical procedure after the patient has been given a local or general anesthetic.

Specialized equipment like CT scans, ultrasound, and MRI help the surgeon to place the seeds correctly. The seeds give off rays continually for weeks, months, or up to a year, and can remain safely in place for the rest of a person’s life. The amount of time that the seeds remain radioactive depends on the dose and the type of radioactive material that is used.

Brachytherapy radiation is placed as close as possible to the cancerous cells so that less of the normal tissue is exposed to the radiation. Interstitial radiation therapy often allows the physician to use a higher dose of radiation for a shorter length of time than is possible with external radiation. It is usually performed within a hospital, and the patient may need to stay there for a few days or longer. Brachytherapy does not make the patient radioactive.

Because it is designed to target the cancerous cells and not harm the surrounding area, brachytherapy is rarely recommended when the cancer has spread beyond the prostate gland.

High-dose Rate Brachytherapy

High-dose rate brachytherapy is a newer form of interstitial radiation treatment involving seeds that are placed in the prostate only temporarily. These seeds stay in place for less than a day and contain more radioactive material than the seeds that stay in place longer. This type of brachytherapy may even be performed in a clinic and may not require hospitalization.

Advantages:

When interstitial radiation therapy is used, the procedure itself is generally painless. In fact, the newer types of brachytherapy, like high-dose rate brachytherapy, usually involve very little discomfort. This type of therapy requires fewer visits to the hospital or physician’s office than other treatments.

Disadvantages:

Although brachytherapy may have fewer side effects than surgery, it has been associated with impotence, urinary incontinence, and bowel problems. Diarrhea, rectal pain, and burning are experienced by some patients, and these side effects may not be easy to treat.

Internal radiation therapy has side effects that are similar to external radiation therapy in general but with a few important differences. Brachytherapy causes impotence less often than do surgery and external beam radiation; however, it may be associated with decreased white blood cell and platelet counts.

In addition, seed insertion usually is not an option for treatment of prostate cancer that has spread beyond the prostate gland.