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Prostate biopsy report explained

ISUP Grade Groups 1 to 5 — What the Number on Your Report Means

Your prostate biopsy report may show an ISUP Grade Group — a number from 1 to 5 that describes how abnormal the cancer cells look under the microscope. It replaced the older Gleason score system and is now the standard way pathologists communicate this finding.

Medically reviewed by Dr. T. Raghavender Reddy, Medical Oncologist, MBBS · DM (Medical Oncology) · MD (Radiation Oncology) · Last reviewed September 2026

  • A number from 1 to 5 — Group 1 is the lowest grade the pathologist can assign. Group 5 is the highest.
  • Not the same as Gleason — Your report may show both. They carry the same information expressed in two different ways.
  • One input, not the whole picture — Your urologist combines the grade group with PSA level, imaging, and your health before recommending anything.
  • Ask the specialist to explain yours — The number on the page is the start of a conversation, not a conclusion you interpret alone.
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ISUP Grade Groups are a five-tier scale — 1 to 5 — used on prostate biopsy reports to describe how abnormal cancer cells look under the microscope. Group 1 is the lowest grade the pathologist assigns; Group 5 is the highest. Your report may show both a grade group and a Gleason score. They carry the same information, expressed differently.

Why did prostate biopsy reports change from Gleason scores to grade groups?

The Gleason system graded prostate cancer on a scale from 2 to 10. In practice, pathologists stopped assigning scores below 6 decades ago. That left the lowest grade ever reported sitting in the middle of a scale that was supposed to start at 2 — confusing for anyone reading the number without that context.

ISUP Grade Groups were adopted at an international pathology consensus meeting in 2014 and endorsed by WHO in 2016. The new scale runs from 1 to 5. Group 1 is genuinely the lowest grade, not a midpoint.

Many laboratories now include both on the same report. If yours does, they are two descriptions of the same finding.

How ISUP Grade Groups map to Gleason scores

ISUP Grade GroupGleason ScorePatternWhat the cells look like
Group 163+3Well-organised; closely resemble normal prostate tissue.
Group 273+4Mostly well-organised, with a proportion of more disorganised cells.
Group 374+3More disorganised cells than well-organised; both patterns present.
Group 484+4, 3+5, or 5+3Mostly poorly organised; some cells show little resemblance to normal tissue.
Group 59–104+5, 5+4, or 5+5Poorly organised throughout, with minimal resemblance to normal prostate tissue.

Terms you will see on a prostate biopsy report

Primary pattern
The pattern making up the largest share of cancer in the sample. It is assigned the first Gleason number.
Secondary pattern
The second-most common pattern in the sample, assigned the second Gleason number. If only one pattern is present, both numbers are the same.
Gleason score
The sum of the primary and secondary pattern numbers. A score of 7 can mean 3+4 or 4+3 — which is why the individual numbers matter as much as the total.
Grade group
The ISUP 1–5 label derived from the Gleason score. It was designed so that 1 genuinely means the lowest grade, not a point partway along a longer scale.
Cores positive
The proportion of biopsy needle samples that contained cancer. Reported alongside the grade group, it tells your urologist how much of the gland the sample shows cancer in.

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What to bring to your appointment

  • Your biopsy report, or a clear photograph of each page
  • The name of the laboratory that processed the sample
  • The date the biopsy was taken
  • A note of the grade group and Gleason score as written on the report
  • Any imaging reports done around the same time — MRI, ultrasound, or bone scan
  • A list of current medications and any other conditions you are being treated for

Does the grade group tell you what treatment you will need?

Not on its own. The grade group is one part of a larger clinical picture. Your urologist will combine it with your PSA level, the number and proportion of cores positive, any imaging findings, your age, and your general health before recommending any course of action.

Bring your full biopsy report to your appointment rather than the grade group number alone. The detail in the pathologist's description — which cores were affected, how much of each core — gives your team information the single number does not.

Did you know?

No Gleason score below 6 was ever used in clinical practice, even though the scale was labelled as running from 2 to 10. The ISUP Grade Group system was introduced specifically to close that gap — so that 1 means the lowest grade assigned, not a number floating in the middle of an unused range.

Source: ISUP 2014 International Society of Urological Pathology Consensus Conference on Gleason Grading of Prostatic Carcinoma

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Common questions

Frequently asked questions

My report says Grade Group 2. What does that mean in plain language?

Grade Group 2 corresponds to a Gleason score of 3+4=7, meaning the pathologist saw cells that were mostly well-organised, with a proportion of more disorganised ones. What that means for your situation — and what comes next — depends on your PSA level, imaging, and other factors your urologist will weigh. The grade group is the starting point for that conversation, not the conclusion.

Why does my report show both a Gleason score and a grade group?

Both describe the same pathology finding. Laboratories include both because many urologists and oncologists trained on the Gleason system and still reference it alongside the newer grade group. You do not need to calculate or convert anything — the report does that. If the two numbers seem inconsistent, ask your specialist to clarify; occasionally laboratories use slightly different conventions for borderline cases.

What does 3+4 mean compared to 4+3 if they both add up to 7?

The first number is the primary pattern — the one that makes up the largest share of cancer in the sample. The second is the secondary pattern. A score of 3+4 means the better-organised pattern is dominant; 4+3 means the more disorganised pattern is dominant. That distinction is why ISUP Grade Groups separate Gleason 7 into Group 2 and Group 3, rather than treating them the same way.

My father's old report shows a Gleason 7. Which grade group is that?

Gleason 7 maps to either Grade Group 2 or Grade Group 3, depending on whether the score is 3+4 or 4+3. The total alone does not tell you which. If the individual pattern numbers appear on the report, the table above will identify the grade group. If the report shows only the total, ask the treating urologist or the original laboratory to confirm which pattern combination was recorded.

Can the grade group change between biopsy and surgery?

Yes, and this is not unusual. A biopsy samples a small number of cores from the prostate; surgery gives the pathologist the whole gland. The full specimen sometimes shows a higher or lower grade than the biopsy suggested. This is called grade migration and is a recognised feature of prostate pathology, not an error. The surgical team will review the final grade after any operation and factor it into follow-up planning.

What happens after the biopsy result?

Your result goes to a urologist or oncologist, who will review it alongside your PSA level and any imaging. They will then explain what the findings mean for your situation and what options are appropriate. In many centres, complex cases are reviewed by a multidisciplinary team before a recommendation is made. If you have not heard back within the timeframe you were given, contact the clinic directly rather than waiting.

Full index

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Every page in this section, grouped by the part of the journey it belongs to. Pick a group to see what is in it.

What Is a Biopsy?

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Types of Biopsy Compared

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Preparing for a Biopsy

What to Expect on the Day of Your Biopsy →

Recovery and Aftercare

After a Biopsy: Recovery, Aftercare and Warning Signs →

Biopsy by Body Part

Biopsy by Body Part: What to Expect at Each Site →

Understanding Your Report

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IHC and Molecular Markers

IHC and Molecular Markers on a Biopsy: What They Mean →

Grading and Scoring Systems

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How Accurate Is a Biopsy?

How Accurate Is a Biopsy? Errors and Second Opinions →

If Your Result Is Benign

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