Radiation
therapy is
the use of high-energy beams or particles to kill cancer cells
or make them unable to grow and divide. The goal is to do
maximum harm to the tumor while doing minimal harm to adjacent
normal tissue. Unlike cancer cells, most normal cells can
repair the damage caused by radiation.
Radiation
is used to treat cancers confined within the prostate gland
or that have spread to nearby tissue. Radiation is also used
to reduce tumor size in more advanced cancers and to provide
relief from uncomfortable symptoms.
Radiation
may be used as the primary method of treatment or as an adjuvant,
or additional, treatment to increase the effectiveness of
another primary therapy, such as radical prostatectomy. In advanced
cancers, hormone therapy may be an adjuvant
to radiation.
Types of radiation therapy
There
are three approaches to radiation treatment for prostate cancer.
- External beam radiation
therapy uses a high-energy x-ray machine
to direct radiation to a target inside the body. Radiation
treatments last a few minutes at a time, usually five days
a week, over the course of several weeks.
- Brachytherapy,
also known as prostate seed implantation or radioactive
seed implantation involves placing tiny radioactive pellets
("seeds") directly inside the prostate tumor. Low-dose seeds
are implanted permanently and give off radiation for several
months before losing their radioactivity. High-dose, or
high-energy, seeds are implanted for less than a day and
deliver a concentrated dose of radiation to the tumor.
- Dose
escalation combines
brachytherapy and external beam radiation therapy and is
used for moderately and highly aggressive tumors.
Appropriate candidates for external beam radiation therapy
- Men
with organ-confined disease. A study published in the January
2000 issue of the journal Cancer compared the results
of external beam radiation therapy and radical prostatectomy
in men with low-risk prostate cancer. Men with low-risk
prostate cancer were those with a PSA of 10 or less, a Gleason
score of 6 or less and no sign of cancer spread beyond the
prostate gland. Both procedures gave men an equally high
likelihood of surviving seven years or longer (97 percent
with radiation vs. 99 percent with surgery) with no detectable
PSA (69 percent with radiation vs. 67 percent with surgery)1.
- Men
whose cancer has extended locally beyond the prostate gland.
- Appropriate
candidates for external beam radiation therapy must be able
to commit to daily treatment sessions for two months. Men
who need to travel frequently or who live far from a radiation
treatment facility may have difficulty making this commitment.
Those who should consider other treatments
- Men
with advanced prostate cancer that has metastasized to areas
distant from the prostate gland.
Appropriate
candidates for brachytherapy
- Men
whose cancer is confined to the prostate gland.
Those who should consider other treatments
- Men
whose cancer has spread beyond the prostate gland.
- Men
who have had extensive transurethral
resection of the prostate (TURP), or whose
resection is poorly healed. Men with small to moderate
TURP may be eligible for brachytherapy; however, the removal
of prostate tissue makes it more difficult to accurately
place the seeds.
- Men
with a life expectancy of less than 5 years (for reasons
other than prostate cancer).
- Men
whose health puts them at unacceptable risk for surgery.
- Men
with a nonpatent (not completely open) anal-rectal canal.
1
Martinez AA, Gonzalez JA, Chung AK, Kestin LL, Balasubramaniam
M, Diokno AC, Ziaja EL, Brabbins DS, Vicini FA. A comparison
of external beam radiation therapy versus radical prostatectomy
for patients with low risk prostate carcinoma diagnosed, staged
and treated at a single institution. Cancer 2000;88:425-32.
More information:
The
Prostate Cancer pages of this Web site are part of the Comprehensive
Prostate Cancer Awareness Program (CPCAP), a major regional
effort to reduce the rates of death and illness caused by
prostate cancer in southwestern Pennsylvania. Funding for
CPCAP is provided by a grant from the Commonwealth of Pennsylvania.
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