Radiation Therapy for Prostate Cancer
Facts About Prostate Cancer
Prostate cancer is the most common malignancy in American men.
- The American Cancer Society estimates that one in every six men will develop prostate cancer in his lifetime
- According to the American Cancer Society, about 186,000 men were diagnosed with prostate cancer in 2008.
- More than 28,000 men are expected to die of the disease in 2008.
- More than 75 percent of prostate cancer is diagnosed in men over age 65.
Prostate cancer is very manageable and often curable. More than 98 percent of men with prostate cancer will live at least five years after diagnosis.
Risk Factors For Prostate Cancer
Incidence of prostate cancer increases with age.
- Median age at diagnosis in Caucasian males is 71.
- African-American men have the highest incidence of prostate cancer in the world.
- Heredity accounts for 5 to 10 percent of cases.
Screening For Prostate Cancer
According to the American Cancer Society, men aged 50 or older should be offered a digital rectal exam (DRE) and a PSA blood test. However, it is a good idea to visit your doctor earlier to establish a baseline PSA level so you can monitor changes.
- Prostate specific antigen (PSA) is a valuable marker for prostate cancer although BPH or infection may also cause a rise in PSA.
- Normal range is 0-4, however, a PSA above 3 in men younger than 60 may be considered abnormal.
- African-American men and men with a family history of prostate cancer should be examined beginning at an earlier age.
Diagnosing Prostate Cancer
Prostate cancer is most often diagnosed through a blood test measuring the amount of prostate specific antigens (PSA) in the body. However, signs and symptoms of prostate cancer can include:
- Changes in urinary flow: Frequency, urgency, hesitancy.
- Frequent nighttime urination.
- Painful urination.
- Blood in urine.
Other conditions that may cause these symptoms include an enlarged prostate (benign prostatic hypertrophy or BPH) or infection.
Radiation Therapy Options for Treating Prostate Cancer
After a diagnosis of prostate cancer has been established with a biopsy, the patient should discuss the treatment options with a radiation oncologist and a urologist. Radiation therapy treatment options to cure prostate cancer include:
- External beam radiotherapy.
- Prostate brachytherapy.
External Beam Radiation
External beam radiation therapy involves a series
of daily outpatient treatments to accurately deliver radiation
to the prostate.
There are two principal methods for delivering external beam radiation.
- 3-dimensional conformal radiotherapy (3D-CRT) combines multiple radiation treatment fields to deliver precise doses of radiation to the prostate. Tailoring each of the radiation beams to accurately focus on the patient's tumor allows coverage of the prostate cancer while at the same time keeping radiation away from nearby organs such as the bladder or rectum.
- Intensity modulated radiation therapy (IMRT) is the most recent
advance in the delivery of radiation. IMRT improves on 3D-CRT
by modifying the intensity of the radiation within each of the
radiation beams. This technique allows more precise adjustment
of radiation doses to the tissues within the target area, potentially
allowing an increased radiation dose to the prostate and reduced
doses to nearby normal tissues. Higher doses to the prostate
translate into a greater chance for cure, while lower doses to
surrounding organs mean fewer side effects.
Both types of external beam radiotherapy are
acceptable treatment; IMRT offers advantages for some but not all
prostate cancer patients. With either type of therapy, painless
radiation treatments are delivered in a series of daily sessions,
each under half-hour in duration, Monday through Friday, for seven
to ten weeks overall.
Potential side effects, including fatigue, increased frequency or discomfort of urination, and loose stools, typically resolve within a few weeks after completing treatments. Impotence is also a potential side effect of any treatment for prostate cancer. However, many patients who receive radiation therapy for prostate cancer are able to maintain sexual function.
Prostate brachytherapy, better known as a seed implant, is often done in the operating room.
There are two methods of delivering internal radiation for prostate cancer:
- Permanent seed implants.
- High-dose rate temporary seed implants.
These treatments are designed to deliver a very high dose of radiation to the tumor by inserting radioactive seeds directly into the prostate gland under ultrasound guidance while the patient is under anesthesia. Isotopes of iodine or palladium are most commonly used. The seeds are approximately four millimeters long and less than a millimeter in diameter. In certain situations, both prostate brachytherapy and external radiation may be recommended to combat the tumor.
The side effects from seed implants are similar to those experienced with external beam radiotherapy. Patients usually experience urinary frequency and discomfort in urination. These effects may be lessened with medication and usually dissipate over the course of three to six months.
Proton Beam Therapy
In a few parts of the country, proton beam therapy is being used to treat prostate cancer.
Proton therapy is administered much the same way as external beam therapy, but it uses protons rather than x-rays to irradiate cancer cells.
Certain patients may benefit from hormone therapy in addition to radiation. In some patients, hormone therapy works with radiation therapy to improve cure rates.