Radiation Therapy for Prostate Cancer [en Español]
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Radiation therapy uses high doses of radiation, such as X-rays, to destroy cancer cells. The radiation damages the genetic material of the cells so that they can't grow. Although radiation damages normal cells as well as cancer cells, the normal cells can repair themselves and function, while the cancer cells cannot.
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. But it also may be used if the cancer has spread to nearby tissue. Radiation is sometimes used after surgery to destroy any remaining cancer cells and to relieve pain from metastatic cancer.
Radiation is delivered in one of two ways.
External-beam radiation therapy uses a
large machine to aim a beam of radiation at your tumor. After the area of
cancer is identified, an ink tattoo no bigger than a pencil tip is placed on
your skin so that the radiation beam can be aimed at the same spot for each
treatment. This helps focus the beam on your cancer to protect nearby healthy
tissue from the radiation. External radiation treatments usually are done 5
days a week for 4 to 8 weeks. If cancer has spread to your bones, shorter
periods of treatment may be given to specific areas to relieve pain.
- Conformal radiotherapy (3D-CRT) uses a three-dimensional planning system to target a strong dose of radiation to the prostate cancer. This helps to protect healthy tissue from radiation.
- Intensity-modulated radiation therapy (IMRT) uses a carefully adjusted amount of radiation. This protects healthy tissues more than conformal radiotherapy does.
- Proton beam therapy uses a different type of energy (protons) rather than X-rays. This allows a higher amount of specifically-directed radiation, which protects nearby healthy tissues (especially the rectum). Sometimes proton therapy is combined with X-ray therapy. It is available only at big medical centers.
Brachytherapy, or internal
radiation therapy, uses dozens of tiny seeds that contain radioactive material.
It may be used to treat early-stage prostate cancer. Needles are used to insert
the seeds through your skin into your prostate. The surgeon uses
ultrasound to locate your prostate and guide the
- High-dose-rate (HDR) brachytherapy uses radioactive material placed into the prostate for a very brief period of time (seconds to minutes) before being removed. The radiation is delivered this way several times.
- Low-dose-rate (LDR) brachytherapy uses a lower dose of radioactive material that is left in place permanently.
Sometimes treatment combines brachytherapy with low-dose external radiation. In other cases, treatment combines surgery with external radiation or hormone therapy may be used along with brachytherapy.
Before radiation therapy is scheduled, your doctor probably will order a bone scan and CT scan to find out whether the cancer has spread to other parts of your body. If it has, your doctor may offer you the option of a clinical trial for treatment.
What To Expect After Treatment
Side effects may last only as long as the treatment, or they may continue and become chronic. Some side effects occur after treatment, such as erection problems. For some men, this problem gets gradually worse over the course of several years after treatment. The long-term effects of radiation therapy on the main body systems are not yet known. Side effects include: footnote 1
- An irritated rectum that can cause an urgent need to pass stool. This is called proctitis.
- An inflamed bladder and urination problems. This is called cystitis.
- An inflamed intestine and diarrhea. This is called enteritis.
- Being unable to have an erection. This is called impotence.
- Being unable to control urination. This is called incontinence.
- Painful urination. This is called dysuria.
- Bleeding from the rectum or blood in the urine.
Why It Is Done
Radiation therapy is used for:
- Cancer that has not spread in generally healthy men who are younger than 70.
- Cancer that has spread to the bones, is not getting better with hormonal treatment, and is causing pain.
- Cancer that has come back in the prostate after surgery.
- Cancer cells that may remain after surgery, especially if all the cancer cannot be removed. This is done very rarely.
How Well It Works
Right now there isn't strong evidence to show what treatment helps men who have localized prostate cancer live longer. High quality studies that compare radiation with surgery for men with localized prostate cancer haven't yet been completed. But a study is currently being done to compare the treatments footnote 2
For treating advanced prostate cancer that has grown beyond the prostate but not into lymph nodes or bones, external-beam radiation combined with hormone drugs can work better than surgery. This treatment often results in controlling cancer growth and in many years of disease-free survival. footnote 1
Radiation therapy also works well to treat pain when prostate cancer has spread to the bone. footnote 3
Radiation treatment for prostate cancer may increase a man's risk for having another cancer later in life, such as bladder or rectal cancer.
Some radiation side effects, like fatigue, are short-term problems that go away with time. But a radiation side effect can become a long-term problem. Common side effects from radiation treatment include:
- Erection problems that develop over time.
- Bowel problems, such as rectal pain, diarrhea, blood in your stool, and rectal leakage.
- Bladder problems, such as a burning feeling when you urinate, blood in your urine, and not being able to control your bladder (urinary incontinence).
- With external-beam radiation, you may have to urinate often or have a sudden urge to urinate (urge incontinence).
- With brachytherapy, you may have a slow or weak urinary stream or be unable to urinate (urinary retention). Or you may leak urine from an overfull bladder without any urge to urinate (overflow incontinence).
For men with high-risk prostate cancer, radiation treatment is given along with hormone therapy. Hormone therapy has side effects, such as the loss of bone density and muscle mass. It can also increase the risk for bone fractures, diabetes, and heart disease.
What To Think About
The goal of radiation therapy is to deliver the highest dose possible to the prostate while protecting the rest of the nearby organs (such as the bladder and rectum) from unnecessary radiation. Newer ways of giving radiation, such as 3D-CRT, IMRT, and proton beam therapy, are more accurate. This has helped to reduce problems caused by radiation.
- National Cancer Institute (2012). Prostate Cancer Treatment (PDQ)—Health Professional Version. Available online: http://www.cancer.gov/cancertopics/pdq/treatment/prostate/HealthProfessional.
- Lane JA, et al. (2014). Active monitoring, radical prostatectomy, or radiotherapy for localised prostate cancer: Study design and diagnostic and baseline results of the ProtecT randomised phase 3 trial. Lancet Oncology, (10): 1109–1118. DOI: 10.1016/S1470-2045(14)70361-4. Accessed August 14, 2015.
- D'Amico AV, et al. (2012). Radiation therapy for prostate cancer. In AJ Wein et al., eds., Campbell-Walsh Urology, 10th ed., vol. 3, pp. 2850–2872. Philadelphia: Saunders.
Current as of: November 20, 2015
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