Gleason Score Explained
The Gleason score is a pathology grade for prostate cancer. It does not tell you how far the cancer has spread; it describes how abnormal the cancer architecture looks under the microscope. The pathologist identifies the most important Gleason growth patterns and adds two numbers, such as 3+3=6, 3+4=7 or 4+3=7. Modern reports also provide an ISUP Grade Group from 1 to 5 because it is easier for patients and clinicians to understand. In general, a higher grade means a greater likelihood of growth and spread, but treatment decisions still require PSA, stage, MRI findings, tumour volume and overall health.
Why does the Gleason score start at 6?
Older Gleason patterns 1 and 2 are no longer assigned to prostate cancer diagnosed on contemporary needle biopsy. As a result, the lowest score usually reported for cancer is 3+3=6. This can sound as though 6 is “middle of a 10-point scale,” but clinically it represents the lowest Grade Group: Grade Group 1.
What do the two numbers mean?
The first number represents the predominant or most clinically relevant pattern according to modern reporting rules, and the second represents the next important pattern. The order matters. Gleason 3+4=7 contains mostly pattern 3 with some pattern 4, while 4+3=7 contains more pattern 4 and generally behaves more aggressively.
Gleason score and Grade Group
| Gleason score | ISUP Grade Group | General interpretation |
|---|---|---|
| 3+3=6 | 1 | Lowest grade commonly assigned; often suitable for active surveillance when other features are low risk. |
| 3+4=7 | 2 | Mostly pattern 3 with a smaller component of pattern 4; intermediate risk depends on other factors. |
| 4+3=7 | 3 | Pattern 4 predominates; higher risk than 3+4 despite the same total of 7. |
| 4+4=8, 3+5=8, 5+3=8 | 4 | High-grade cancer. |
| 4+5=9, 5+4=9, 5+5=10 | 5 | Highest Grade Group and generally more aggressive biology. |
What is Gleason pattern 4?
Pattern 4 refers to several abnormal glandular architectures that are more aggressive than pattern 3. The amount of pattern 4 can matter in Grade Group 2 disease and may influence whether active surveillance is reasonable. Some pathology reports also describe cribriform architecture or intraductal carcinoma because these features can carry additional prognostic importance.
Can the grade change after surgery?
Yes. A biopsy samples only part of the prostate. The entire prostate removed at radical prostatectomy provides much more tissue, so the final surgical Grade Group can be higher, lower or the same as the biopsy grade. MRI-targeted biopsy reduces but does not eliminate sampling differences.
Grade is not the same as stage
Grade describes microscopic aggressiveness. Stage describes anatomic extent — whether cancer is confined to the prostate, extends outside it, involves lymph nodes or has metastasized. A treatment plan needs both.
Why the amount of Gleason pattern 4 can matter
Two cancers can both be reported as Gleason 3+4=7 yet contain very different amounts of pattern 4. A small focus of pattern 4 in otherwise pattern-3 cancer may behave differently from a tumour with extensive pattern 4. Pathologists may report the percentage of pattern 4, and features such as cribriform or intraductal carcinoma can add important adverse information.
This is particularly relevant when discussing active surveillance in selected Grade Group 2 disease. The label “3+4” is not the whole risk assessment; PSA density, MRI, number and length of involved cores, pattern-4 volume and other pathological features all matter.
When to seek urgent medical care
A Gleason or Grade Group result is not an emergency by itself. Urgent assessment is appropriate for inability to pass urine, heavy haematuria with clots, fever after a recent biopsy, or new severe back pain with leg weakness, numbness or loss of bladder/bowel control. Otherwise, the priority is a timely appointment to interpret grade together with PSA, MRI and stage.
Consultation checklist
- Full biopsy report, not only the final Gleason number.
- Number of positive cores and percentage/length of cancer in each core.
- MRI report and PSA density.
- PSA value at diagnosis.
- Any mention of cribriform pattern, intraductal carcinoma or perineural invasion if reported.
FAQs
Is Gleason 6 low risk?
Gleason 3+3=6 is Grade Group 1, the lowest modern grade. If PSA, stage and tumour volume are also favourable, active surveillance is often preferred.
Is Gleason 7 one category?
No. 3+4=7 is Grade Group 2 and 4+3=7 is Grade Group 3. The latter generally has more aggressive biology because pattern 4 predominates.
Can Gleason score improve without treatment?
The true cancer grade does not usually “improve” biologically. Different biopsies can sample different areas, so reported grade may vary because of sampling.
Does Gleason 9 mean stage 9?
No. Gleason 9 is a high pathological grade, not a cancer stage.
Which is more important, PSA or Gleason score?
Neither should be interpreted alone. Grade, PSA, stage, MRI and tumour volume together determine risk.
Related reading
- ISUP Grade Group Explained
- Prostate Biopsy: Procedure and Risks
- Localized Prostate Cancer Explained
- Active Surveillance in Prostate Cancer
- Metastatic Prostate Cancer Explained
- Urologist in Latur
References
- Epstein JI, Egevad L, Amin MB, et al. The 2014 International Society of Urological Pathology (ISUP) Consensus Conference on Gleason Grading of Prostatic Carcinoma. Am J Surg Pathol. 2016;40(2):244-252.
- European Association of Urology (EAU). EAU Guidelines on Prostate Cancer. 2026 edition https://uroweb.org/guidelines/prostate-cancer
- National Cancer Institute. Prostate Cancer Treatment (PDQ®)–Patient Version https://www.cancer.gov/types/prostate/patient/prostate-treatment-pdq
- American Urological Association/ASTRO. Clinically Localized Prostate Cancer Guideline (2022; amended 2026) https://www.auanet.org/guidelines-and-quality/guidelines/clinically-localized-prostate-cancer-aua/astro-guideline-2022