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Background:
Anatomy:
The prostate gland
produces most of the liquid part of the semen in which the
sperm are carried. The gland is located just below the bladder
above the base of the penis. Directly behind the prostate
gland is the rectum. The prostate gland itself is approximately
the size of a walnut (30 cc) in the young adult male. As
men grow older the prostate tends to grow larger (benign prostatic
hypertrophy).
Epidemiology:
Cancer of the prostate
is extremely common; luckily, many men who have prostate cancer
never suffer any ill effects. This is because prostate cancer
is often an indolent (slow growing) process which men die
“of” and not “from.”
However, as it
is a common cancer in cases where it does progress, it represents
a significant cause of death in this country. Approximately
40, 000 men die of prostate cancer. It is believed that many
of those deaths each year could have been prevented if the
cancer had been caught early enough and treated effectively.
The causes of
prostate cancer are not well-understood. There is no single
substance which has been proven to cause the development of
this disease. There is some evidence that a typical “western”
diet of red meat and fat may predispose to some extent, although
prostate cancer is seen in all parts of the world. There
is no evidence that heredity or sexual activity play much
of a role in the development of prostate cancer.
STAGING:
Stage A prostate
cancer is a disease which is identified only at the time of
a transurethral resection (TURP). This type of surgery is
typically done as the treatment for benign prostatic hypertrophy
and involves scraping out an inner core of the prostate through
the penis.
Stage B cancer
of the prostate means that the disease is indicated based
on either an elevated PSA blood test or a palpable nodule
in the prostate.
Stage C disease
means that the cancer extends through the capsule of the gland
into the tissue immediately adjacent to the prostate. This
can be identified either by digital examination or by x-ray
or ultrasound picture.
Stage D cancer
of the prostate has spread to other parts of the body such
as lymph nodes or bone.
Two other factors
beyond the A, B, C, D staging carry important prognostic information
in prostate cancer. One of these is the PSA blood test; the
other is the Gleason score.
PSA , or prostatic
specific antigen, is a commonly performed blood test. The
normal value for the PSA is 0-4 ng/ml. When the PSA is above
4 ng/ml a patient should be checked for prostate cancer.
In patients who have prostate cancer diagnosed, the higher
the PSA, the less optimistic the prognosis. Thus, patients
with PSA values above 10 tend to respond less effectively
to the forms of treatment.
The Gleason score
is a subjective analysis of the biopsy specimen by the pathologist.
Using a regular microscope, the pathologist grades the cancer
based on how poorly differentiated the cells appear. Very
poorly differentiated cancers (Gleason scores 8, 9 , or 10)
tend to have a more aggressive pattern of spread. Conversely,
patients with cancers with low Gleason scores ( 2, 3, or 4)
tend to have the longest life expectancy.
TREATMENT OPTIONS:
Surgery:
Surgical treatment
of prostate cancer consists of a radical prostatectomy. This
is a major operation which involves removing the prostate
and usually the lymph nodes adjacent to the prostate in the
pelvis. Almost all patients experience partial or total impotency.
A significant portion, (approximately 10%) also have significant
difficulty with control of urine flow. Many urologists believe
these are acceptable side effects because they feel that the
cure with radical prostatectomy is better than with any other
form of treatment for prostate cancer (although this has not
been proven).
Radiation:
Another good option
in the treatment of prostate cancer is radiation therapy.
Radiation therapy has a cure rate which is nearly as good
as surgery and with less likelihood of side effects. The
impotency rate after radiation therapy is somewhat lower than
surgery and urinary incontinence is unlikely.
Hormone treatment:
Taking away the
main male hormone, testosterone, causes a temporary regression
in prostate cancer. There are two ways of eliminating testosterone.
One, the old-fashioned method, is castration (sometimes called
orchiectomy). A more modern approach involves medicine.
A drug such as Lupron or Zoladex is injected once every
three months, which causes the testicles to stop producing
testosterone.
Unfortunately,
there are two drawbacks to this hormonal approach. First
of all, any hormone treatment is only temporary. Eventually
the cancer cells “figure out” how to grow without the hormone
present and the patient can suffer from advanced cancer.
The other problem
with hormone treatment involves the side-effects. When a
male is deprived of testosterone he suffers certain ill effects, including
loss of libido (interest in sex), muscle weakness, fatigue
and hot flashes.
RADIATION THERAPY:
Typical course:
Radiation therapy
for the prostate is given in small, daily fractions. Each
one of these fractions or treatments consists of about 1.8
gray (a gray is a measurer of radiation dosage) administered
through four separate fields, one from the front, another
from the back and one from each side. Typically patients
do not experience any immediate sensation from the radiation.
The treatment itself takes only a few minutes and the patient
can drive home or to a restaurant without any ill effects.
The radiation therapy fields are lined under careful computer-based
CT scan images which show the radiation oncologist where the
cancer is located.
External treatment
typically consists of about 40 treatments administered five
days a week over eight weeks. Gradually, as the treatment
progresses, some side effects do occur. These can include
irritation of the bladder so that the patient has to urinate
more frequently, and irritation of the rectum so that the
patient has to have more frequent bowel movements. Medications
are available to treat both of these side-effects and the
are usually not severe enough to interfere with the patient’s
lifestyle.
External versus
seed treatments:
Some patients receive
some or all of their radiation with seed implantation. There
is a separate description of this on our web site. The advantage
of the radiation seeds is that the radiation oncologist, in
conjunction with the urologist, can limit the radiation to
just the interior of the prostate gland without giving any
significant dose to adjacent organs. This can lessen the
side effects on the bladder and the rectum.
The disadvantage
of the seeds is also related to their limited scope of treatment.
All of the radiation is confined to the prostate gland. This
means that if some cancer cells have escaped from the prostate
gland and are lodged in adjacent lymph nodes (and these can
be so tiny that no tests can detect them), seeds will not
be effective against them. This is where external beam radiation
therapy can be helpful. By giving some of the radiation externally,
the disease in the lymph nodes can be treated.
Long term side-effects
of radiation:
Major long tem
side effects of radiation are unusual. The radiation can
cause temporary irritation of the rectum and the bladder,
but permanent damage is rare.
Peter
H. Blitzer, MD, FACR, FACRO
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