The Early Detection of Prostate Cancer
Early detection is
especially important in prostate cancer, because when this form of cancer is
the chances for a cure are greatly increased.
digital rectal examination is
a simple procedure where the physician inserts a lubricated gloved finger into
rectum. This examination can help the doctor detect a mass. To confirm
the presence of cancer, the urologist will perform
a biopsy, which involves
obtaining a small sample of the prostate to determine whether it contains cancer
cells. In order to
tell if the cancer has spread outside the prostate, several
tests are useful for detecting and staging prostate cancer. Not all
tests are needed in all men.
prostate-specific antigen (PSA) test is a blood test that can indicate the
presence of prostate cancer. However, the
PSA test is sometimes difficult to
interpret because PSA is produced by both normal and cancerous prostate cells.In general, the higher the PSA level, the greater the chance that the cancer has
spread beyond the prostate.
ultrasonography is a safe and easy way to "see" the prostate gland.
Ultrasound provides an
image of the prostate that the doctor can use to measure the size of the
prostate, look for
cancerous tissue, and calculate the PSA density (the PSA level divided by the
size of the prostate). A needle biopsy
of the prostate is usually performed under ultrasound guidance.
A prostate biopsy
analysis of the tissue gives important information about the cancer. The
tumor grade is determined
by examining the tissue under a microscope to
measure the amount of disorganization of cells. A Gleason grade, which
ranges from 2 to 10, is one scale that can be used to estimate the tumor's
growth rate. Generally, the lower the grade,
the slower the cancer grows. Most
localized cancers of the prostate are of an intermediate grade, (Gleason grades
4, 5 or 6).
The Gleason grades for the two most prominent groups of cells is
called the Gleason Score.
The Five Gleason Grades
||Cancer is well
||Cancer is still
well differentiated, but is arranged more loosely and is more irregular in
||Most common grade
of prostate cancer. Cancer is moderately differentiated, varying in size
from small to large
||Cancer is poorly
differentiated, unable to form separate units, highly irregular, and has
distorted shapes; progressive invasion of neighboring tissue
undifferentiated and bears no resemblance to normal cells.
It is important to understand that at least two physicians work with you through
the diagnosis phase, one who will analyze
your prostate disease (the
pathologist) and one who will detect and treat it (usually a urologist
and/or radiation oncologist).
At present, the only definitive method for
determining the presence or absence of cancer in a prostate gland is by the
and interpretation of tissue samples by a pathologist. The
interpretation of tissue samples is a result of the pathologistís
medical judgment, and legitimate differences of opinion can exist. A second opinion
might be valuable in certain circumstances.
bone scan produces a nuclear image of the bones. this test, which may detect the
spread of cancer to the bones, may not
be necessary in all patients, especially
those with small cancers, low PSA levels and low Gleason grades.
Computed tomographic scan (CT scan) is an X-ray procedure that produces
cross-sectional images of the body. The CT scan
may help detect lymph nodes in
the pelvis that are enlarged because of cancer. Generally, a CT scan is used
only if the cancer
is large, of a high grade, or associated with a very high PSA
The lymph nodes in the pelvis usually are the first place that cancer
spreads from the prostate. The doctor can make a rough
estimate of how likely it
is that cancer has spread to the lymph nodes. This estimate is based on the
cancer's size in the prostate
and on results of the biopsy. A high PSA level
also may indicate that the cancer has entered the lymph nodes. However, cancer
in the pelvic lymph nodes often is microscopic. If there is a high risk that the
cancer has spread to the lymph nodes, the doctor
may recommend that they be
surgically removed and examined under a microscope. Because there are many lymph
elsewhere in the body, the loss of some of the pelvic lymph nodes does not
usually cause problems.
Radio-labeled Antibody Scans
An antibody that binds to the prostate specific membrane antigen (PSMA) may be
able to detect cancer that has spread beyond
the prostate and into soft tissue.
Many prostate cancer cells produce the PSMA protein, which stays attached to the
During the scan an antibody, with radioactive material attached,
is injected into a vein. The antibody then circulates throughout the
only binds where it finds the PSMA protein. After four or five days, the
antibody that does not bind to the PSMA is
cleared from the body. Ideally, most
of the remaining antibody will be bound to the prostate cells bearing the PSMA. In disease
recurrence following prostatectomy, this type of test may indicate whether the
cancer is limited to the prostate and may be useful
in identifying patients most likely to benefit from salvage local
therapy. Unfortunately, there are limitations to this type of scan,
may be difficult to interpret. Currently, the only commercially available scan
of this type is ProstaScint.