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Once your cancer has been identified, the doctor wants to know
how large it is and how far it has spread. Depending on its size and
spread, your doctor will stage your tumor. Information on your tumor
stage, along with tumor grade and PSA level, is central to choosing
your treatment and to monitoring its success.
Tumor stages are:
Localized
Stage I or A or T1: a tumor that cannot be felt (nonpalpable).
Stage II or B or T2: a tumor that can be felt (palpable)
but is confined to the prostate gland.
Regional
Stage III or C or T3: a tumor that has grown through the
prostate capsule, perhaps into the seminal vesicles.
T4: a tumor that has grown into nearby muscles and organs.
Metastatic
Stage IV or D and N+ or M+: tumors that have metastasized to
the regional (pelvic) lymph nodes (N+) or more distant parts of the
body (M+).
Each of these stages is subdivided into more precise categories.
In 1990, two-thirds of newly diagnosed prostate cancers were
Stage I or II (clinically localized). Slightly more than 10 percent
were Stage III (regional), while about 20 percent were Stage IV (metastatic).
The main tests used for clinical staging of prostate cancer are
DRE, PSA, and transrectal ultrasound (TRUS). Bone scans may be used
when distant metastases are suspected.
The digital rectal exam (DRE), a procedure in which the doctor
inserts a gloved finger into the rectum to examine the rectum and
prostate to look for an irregular or abnormally firm area, helps to
gauge tumor size, and it may show if the cancer has spread into
nearby tissues.
PSA tests are playing an increasingly common role in cancer
staging. Elevated PSA levels in the blood correlate roughly with the
volume of cancer in the prostate, with the stage and grade of the
tumor, and with the presence or absence of cancer metastases or
growths in other tissues.
Valuable information about tumor size and location can also be
obtained from TRUS used to guide the biopsy in sampling abnormal
areas of the prostate. TRUS uses an ultrsound probe inserted in the
rectum to visualize the area on a screen.
The pathologist's evaluation of the biopsy samples also helps to
establish the clinical stage (size and extent) of a cancer. The
pathologist tallies how many of the tissue samples contain cancer,
notes whether any of the samples are more than half cancerous, and
determines a Gleason score.
When clinical staging suggests that cancer has spread to the
lymph nodes or beyond, radionnuclide bone scans can be used to look
for metastases to bone, a common site of prostate cancer spread.
However, research now shows that patients with PSA levels of 10 ng/ml
or less, without bone pain, are so unlikely to have bone
metastases-regardless of tumor stage or grade-that doctors often
recommend that these patients can skip the bone scan.
Sophisticated imaging techniques such as computed tomography (CT)
and magnetic resonance imaging (MRI) can also help to uncover
distant metastases. Like bone scans, however, such tests may be
unnecessary for some men. Recent studies indicate that when prostate
cancer is clinically localized -the situation for two-thirds of
newly diagnosed cases-CT and MRI add little to the information
available through DRE, PSA, and TRUS.
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