MAGENT

Gleason score: the original 1974 pattern sum

The Gleason score is the sum of two histologic patterns seen in prostate adenocarcinoma: the primary (most common) pattern and the secondary pattern. Each pattern is a whole number from 1 to 5, so the score runs from 2 to 10. Magent's calculator adds two patterns that a pathologist has already assigned, using the original 1974 system. It doesn't look at slides.

Not a medical device. Not a diagnosis or dosing recommendation.

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What is the Gleason score?

Under the microscope, prostate adenocarcinoma shows glands arranged in recognisable patterns. Gleason described five of them, numbered 1 to 5, with higher numbers for architecture that looks less like normal gland. Most tumours show more than one pattern. The original system records the two that cover the most area and adds them.

That sum is the Gleason score. The same total can be built in two ways (2 + 1 or 1 + 2, for example), which is why reports give the two patterns as well as the total.

Magent's calculator takes the primary and secondary pattern numbers and returns their sum, the maximum of 10, and the two inputs as points.

Which Gleason system this is

This page covers the 1974 system as published. Modern pathology reports use the ISUP-modified Gleason grading and report Grade Groups 1 to 5 alongside the score. The calculator doesn't apply the modified pattern rules and doesn't convert a score to a Grade Group.

The Gleason score formula

Gleason score = primary pattern + secondary pattern

primary pattern     1 to 5   (most common pattern, assigned by the pathologist)
secondary pattern   1 to 5   (second most common pattern)
score               2 to 10

Exact expression the calculator uses:

Gleason score = primary + secondary; each pattern 1-5 as assigned by the caller (Gleason 1974); range 2-10. magent does not read slides. Not ISUP/Epstein 2016 Grade Groups. Not 2005 ISUP modified pattern rules.

Inputs

InputMeaningAllowed values
primaryPrimary (predominant) Gleason patternWhole number 1 to 5
secondarySecondary Gleason patternWhole number 1 to 5

Both inputs are required. Fractions, 0, 6 and Roman numerals are rejected.

How the calculation works

  1. Take the primary pattern. This is the pattern covering the largest area.
  2. Take the secondary pattern. This is the next most extensive pattern.
  3. Add them. The result is between 2 and 10.

The order of the inputs matters for the report but not for the sum. Primary 2 with secondary 1 and primary 1 with secondary 2 both add to 3.

Worked examples

These use Magent's own expected values for the calculator.

Example 1: the lowest possible sum

  1. Primary pattern 1, secondary pattern 1.
  2. 1 + 1.
  3. Gleason score 2 out of 10. This is the floor of the 1974 scale, not a zero total.

Example 2: primary 2, secondary 1

  1. Primary pattern 2, secondary pattern 1.
  2. 2 + 1.
  3. Gleason score 3.

Example 3: primary 3, secondary 3

  1. Primary pattern 3, secondary pattern 3.
  2. 3 + 3.
  3. Gleason score 6.

Example 4: primary 4, secondary 4

  1. Primary pattern 4, secondary pattern 4.
  2. 4 + 4.
  3. Gleason score 8. The calculator returns the sum and doesn't add a Grade Group.

Example 5: the highest possible sum

  1. Primary pattern 5, secondary pattern 5.
  2. 5 + 5.
  3. Gleason score 10, the maximum.

History of the Gleason score

Donald Gleason and George Mellinger, working with the Veterans Administration Cooperative Urological Research Group, published the combined grading system in the Journal of Urology in 1974. The paper's title describes predicting prognosis for prostatic adenocarcinoma by combining histological grading with clinical staging. The pattern sum from that paper is what this calculator applies.

When it's used

The sum is worked out after a pathologist has graded prostate tissue and recorded the two most extensive patterns.

Where it's used

Pathology reports for prostate biopsies and prostatectomy specimens carry Gleason grading, and the score is read in urology and oncology settings.

Who uses it

Pathologists assign the patterns. Urologists, oncologists and other clinicians read the score. The calculator adds the two numbers it is given and nothing else.

Limits of the calculation

  • The calculator doesn't grade tissue. The patterns must come from a pathologist.
  • It applies the 1974 sum. It doesn't apply the later ISUP pattern rules and doesn't output Grade Groups.
  • It doesn't label a score as well, moderately or poorly differentiated.
  • A total alone hides how it was built. A report should keep the primary and secondary patterns with the score.
  • This page doesn't say what any score means for a particular person.

Clinical decisions belong to a qualified clinician who knows the patient.

  • Fuhrman grade is a nuclear grade for kidney cancer, 1 to 4. The Gleason score is an architectural pattern sum for prostate cancer.
  • UISS groups kidney cancer by stage, Fuhrman grade and performance status. It doesn't use Gleason patterns.

Glossary

  • Pattern: one of the five gland arrangements Gleason described, numbered 1 to 5.
  • Primary pattern: the pattern covering the largest area of tumour.
  • Secondary pattern: the next most extensive pattern.
  • Grade Group: a later 1 to 5 grouping used in modern reports. Not returned here.

Common mistakes

  • Reading a 1974 score as a Grade Group. They are different scales. The calculator doesn't convert one to the other.
  • Entering a Grade Group as a pattern. The inputs are patterns 1 to 5, not groups.
  • Dropping the two patterns. A score of 3 can be 2 + 1 or 1 + 2. Keep both numbers.
  • Expecting a zero. The lowest 1974 sum is 2.

Source

Gleason DF, Mellinger GT. Prediction of prognosis for prostatic adenocarcinoma by combined histological grading and clinical staging. J Urol. 1974;111(1):58-64. DOI: 10.1016/S0022-5347(17)59889-4. PMID: 4813554

Frequently asked questions

What is a Gleason score?

The sum of the primary and secondary Gleason patterns in prostate adenocarcinoma, each 1 to 5, giving a total of 2 to 10.

Is the Gleason score the same as a Grade Group?

No. Grade Groups 1 to 5 are a later grouping used in modern reports. This calculator returns the 1974 sum and doesn't produce a Grade Group.

What is the highest Gleason score?

10, with both patterns at 5.

Why does the order of the patterns matter?

The sum is the same either way, but the primary pattern is the one covering the most tumour. Reports keep both numbers for that reason.

Does the calculator read the biopsy?

No. A pathologist assigns the two patterns. The calculator adds them.