What is the Gleason score?

The Gleason score is the sum of the primary grade (most common architectural pattern) and the secondary grade (second most common pattern), each rated 1–5 by a pathologist. Scores range from 2 (1+1) to 10 (5+5). Higher scores indicate more aggressive cancer.

What are Grade Groups?

Grade Groups (1–5) were introduced in 2016 to simplify Gleason scores into five prognostic tiers. Grade Group 1 (Gleason ≤6) is the least aggressive; Grade Group 5 (Gleason 9–10) is the most aggressive. They map more directly to outcomes than the older score alone.

Why does 3+4 differ from 4+3 if the sum is the same?

Gleason 3+4 and 4+3 both sum to 7, but 4+3 carries a worse prognosis because grade 4 (poorly formed glands) is the dominant pattern. This is why the primary grade is listed first and drives the Grade Group assignment (3+4 = Grade Group 2; 4+3 = Grade Group 3).

Is a Gleason score of 6 always low-risk?

Gleason 6 (3+3) is Grade Group 1 and is considered favorable-risk cancer. However, overall risk also depends on PSA level, tumor stage, and biopsy core involvement. Always discuss results with a urologist or oncologist.

Are Gleason scores 1 and 2 still used?

Grades 1 and 2 are rarely assigned today. Modern pathology guidelines (ISUP 2014/2016) discourage reporting Gleason scores below 6 on needle biopsy because they are difficult to reproduce and may represent non-cancerous tissue. Most contemporary reports start at Gleason 3+3=6.

Gleason Score Reference

Select primary and secondary Gleason grades to look up the combined score, Grade Group (1–5), and what it means clinically.

Enter Gleason Grades

Primary Grade (dominant pattern)

Secondary Grade (second most common)

Select both grades above to see the Gleason score and Grade Group.

Full Reference Table

ISUP 2016 Grade Group classification

Primary	Secondary	Score	Grade Group	Risk

Summary

The Gleason grading system is the standard method pathologists use to describe prostate cancer aggressiveness. A primary grade and secondary grade — each from 1 to 5 — are added together to produce a Gleason score from 2 to 10. The 2016 ISUP Grade Group system (1–5) maps these combinations into five prognostic tiers that correlate more cleanly with patient outcomes.

How it works

Select primary and secondary grades to compute the Gleason sum.
The tool maps the grade combination to one of five Grade Groups per ISUP 2016 guidelines.
A plain-English interpretation and typical prognosis context are shown for each group.

Use cases

Understand a biopsy pathology report after a prostate cancer diagnosis.
Cross-reference Gleason score with the newer Grade Group system.
Educate patients or students on prostate cancer grading terminology.
Quickly look up prognosis tiers without consulting a textbook.
Compare how the same combined score can differ depending on grade order.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu