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Gleason Score/Grade and Prostate Health
- What is a
Gleason Score?
The Gleason score
was invented in 1966 by Dr. Donald Gleason, a pathologist.
He based the score on information derived from studies of
the biopsies of nearly 3,000 patients who had been diagnosed
with prostate cancer. Pathologists worldwide rely on the
Gleason score. The score provides an effective measurement
that helps your doctor determine how severe your prostate
cancer is, based on the appearance of the cancer cells when
viewed under a microscope. All cancer looks abnormal to a
pathologist, but low-grade cancers have cells that often
look similar to healthy cells from the gland or organ that
has been affected by the cancer. As a result, the
pathologist can recognize that she's looking at prostate
cells under the microscope. But when the cancer is
aggressive, the cancer cells look less and less like normal
prostate cells (or any other kind of cells).
Pathologists find
the Gleason grading system to be very reliable. For example,
if the Gleason score indicates that the cancer is an
intermediate risk cancer (a Gleason score of 7) it nearly
always is an intermediate risk. As a result, doctors
can make predictions from Gleason grades. The more distorted
and aggressive the cancer looks, the higher the Gleason
grade, and the more aggressive the cancer behaves in the
body.
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- How does the
Gleason Score work?
The pathologist looks at the biopsied
tissue samples through a microscope to determine where the
cancer is the most prominent (the primary grade) and then
where it's next most prominent (the secondary grade). Next,
he assigns a score from 1 to 5 to each area: one score for
the primary grade and one score for the secondary grade. The
Gleason score is the sum of the primary and secondary
grades
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What are the 5 Gleason Grades?
Grade 1: The least common
pattern, especially in needle biopsies. Consists of a
circumscribed mass of evenly placed uniform glands that
closely resemble normal prostate glands
Grade 2: Cancer glands are
similar to those seen in Grade 1 but do not form a
circumscribed mass. There may be slight variation in
size, shape, and spacing of the glands. The glands can
be seen infiltrating (spreading) through the surrounding
stroma. Click on
Gleason Pattern 2
Grade 3: The most common
pattern showing considerable variation in size, shape,
and spacing of the glands. Irregular infiltration of the
surrounding stroma may impart a ragged appearance to the
cancer focus when seen at low-magnification under the
microscope.Gleason Pattern 3
Grade 4: The most important
feature of this grade is fusion of glands forming an
anastomosing network punctuated by glandular lumens.
Glands are no longer recognized as individual units.Gleason
Pattern 4
Grade 5: The cancer cells form
solid sheets and clusters or may infiltrate the prostate
as individual cells. Necrosis may be present. There is
no attempt at gland formation by cancer.Gleason
Pattern 5
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- What is the
Significance of the Gleason Score?
The Gleason score indicates the
aggressiveness of the prostate tumor. Patterns 1 and 2 are
well differentiated; Pattern 3 is moderately-differentiated;
and Patterns 4 and 5 are poorly differentiated. What is
differentiation? Well, cells that are completely
differentiated know exactly what they are doing in life.
Perfectly differentiated prostate cells are happy to go
about their business in the prostate making PSA and
ejaculatory juices. They look and act like the mature
prostate cells they are. They interact with other perfectly
differentiated prostate cells to create the tiny tubular
structures that the prostate requires to deliver its product
to the urethra. Once they become malignant, however, the
prostate cells become less differentiated and behave less
like well-disciplined prostate cells. The tubules they make
with other malignant cells are distorted and haphazardly
arranged. As they become even less differentiated, they form
solid clumps and may become anti-social, preferring to go
off on their own and not even attempt to make tubules with
other cells.
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- How do I
Interpret the Gleason Score?
The Gleason score is written as the sum of the two most prominent Gleason
patterns. The lowest possible Gleason score is 1+1=2 when both the primary and
secondary patterns are Grade 1. The highest possible Gleason score is 5+5=10
when both the primary and secondary patterns are Grade 5 . So a Gleason
score of 2+3=5 has a dominant well-differentiated pattern (i.e., pattern 2) and
a less dominant moderately-differentiated pattern (i.e., pattern 3). A score of
4+3=7 means that a poorly differentiated component (pattern 4) is dominant. If
95% or more of the tumor is composed of one pattern, the corresponding number is
counted twice; thus, a wholly moderately-differentiated tumor would be scored
3+3=6. Note: not all scores are equal. A score 7 from 3+4 is better than one
from 4+3. So if you want to know the real deal on your Gleason score, get a
breakdown of the two numbers that comprise the score. Ask your doctor for your
Gleason score, starting with the primary grade first, followed by the secondary
grade and then the total.
Gleason Scores
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1+1=2 |
Lowest possible Gleason
score, where both the
primary and secondary
patterns have a Gleason
grade of 1 |
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1+2=3 |
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2+1=3 |
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2+2=4 |
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2+3=5 |
Very typical Gleason score. |
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3+2=5 |
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3+3=6 |
Most commonly observed
Gleason score. |
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3+4=7 |
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4+3=7 |
Very typical Gleason score. |
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4+4=8 |
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4+5=9 |
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5+4=9 |
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5+5=10 |
Highest possible Gleason
score, when the primary and
secondary patterns both have
the most disordered Gleason
grades of 5. |
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