How Are the Six Prostate Cancer Risk Groups Defined?

Prostate cancer is not just one disease; it ranges from very slow-growing tumors to aggressive cancers that require immediate treatment. To help you and your doctor decide on the best treatment plan, medical teams use a six-tier risk system (based on the National Comprehensive Cancer Network, or NCCN, guidelines) for clinically localized prostate cancer ^[1]. These groups—ranging from very-low to very-high risk—estimate the statistical likelihood of the cancer progressing or recurring. They are based on specific details from your biopsy, physical exam, and blood tests.

Scope: What Are These Categories For?

These groups apply only to prostate cancer that has not spread to lymph nodes or distant organs ^[1]. If imaging shows spread (cN1 or M1 disease), treatment follows a different framework. The risk group is a pre-treatment estimate used to guide decisions; it does not replace staging imaging or guarantee your personal biological outcome ^[1].

The Key Factors Used to Determine Your Risk

To find your risk group, your doctor looks at several specific inputs from your diagnostic tests:

• PSA (Prostate-Specific Antigen): The level of this protein in your blood.
• Grade Group (and Gleason Score): A grading system that describes how abnormal the cancer cells look under a microscope ^[1]. Modern pathology uses a 1-to-5 scale:
  • Grade Group 1: Gleason 3+3=6 (Scores 2–5 are rarely assigned in modern systems) ^[2][3].
  • Grade Group 2: Gleason 3+4=7 ^[4].
  • Grade Group 3: Gleason 4+3=7 ^[5].
  • Grade Group 4: Gleason 8 ^[6].
  • Grade Group 5: Gleason 9 or 10 ^[6].
• Clinical T Stage: An estimate of how far the tumor has grown, based primarily on a physical exam (digital rectal exam) and sometimes informed by imaging ^[1].
  • T1c: The tumor cannot be felt during an exam but was found on a needle biopsy (often done because of a high PSA) ^[7].
  • T2a, T2b, T2c: The tumor can be felt but is confined to the prostate. (T2a covers less than half of one side, T2b covers more than half of one side, T2c involves both sides) ^[2][8].
  • T3a: The cancer is growing just outside the prostate capsule (the outer lining of the prostate), also called extraprostatic extension ^[9].
  • T3b: The cancer has invaded the seminal vesicles (the glands behind the prostate that produce semen) ^[10].
  • T4: The cancer has invaded other specific nearby structures like the bladder or rectum ^[11].
• Biopsy Core Details: The absolute number of positive cores (samples containing cancer) and the percentage of each core involved. Note: If you had both MRI-targeted and systematic biopsies, calculating the exact percentage of positive cores can be complex. Rely on your doctor’s calculation rather than just dividing the numbers yourself ^[12][13].
• PSA Density: Your PSA level divided by the volume of your prostate ^[14].

The Six Risk Groups Defined

1. Very-Low Risk

This category indicates a very low likelihood of early progression. To be in this group, all of the following must be true:

• Clinical stage T1c ^[7].
• Grade Group 1 (Gleason 3+3=6) ^[7].
• PSA level less than 10 ng/mL ^[7].
• PSA density less than 0.15 ng/mL/cm³ ^[7].
• Fewer than 3 positive biopsy cores (usually meaning exactly 1 or 2 cores containing cancer) ^[7][15].
• No more than 50% cancer involvement in any single biopsy core ^[7][15].

2. Low Risk

This category also indicates a low likelihood of progression. You are in this group if your cancer meets the core low-risk criteria but fails at least one of the stricter very-low criteria (like stage, PSA density, or core counts). To be in this group, all of these must be true:

• Clinical stage T1 to T2a ^[2].
• Grade Group 1 (Gleason 3+3=6) ^[2].
• PSA level less than 10 ng/mL ^[2].

3. Favorable-Intermediate Risk

Intermediate risk implies a moderate chance of progression, but “favorable” means it lacks the most concerning intermediate features. You must have all of the following to be in this category:

• Exactly one intermediate-risk factor. (The three intermediate factors are: a PSA of 10 to 20 ng/mL inclusive, clinical stage T2b–T2c, or Grade Group 2 or 3) ^[8][12][4].
• A Grade Group of 1 or 2 (meaning the primary, most common Gleason pattern is 3, such as in Gleason 3+3 or 3+4). Having Grade Group 3 (Gleason 4+3=7) automatically excludes you from the favorable group ^[4][12].
• Less than 50% of your total biopsy cores containing cancer ^[12][4].

4. Unfavorable-Intermediate Risk

This group has features suggesting a higher likelihood of progression than the favorable group. You are placed in this category if you have any one of the following unfavorable features:

• Two or more intermediate-risk factors ^[5][4].
• Grade Group 3 (a primary Gleason pattern of 4, such as Gleason 4+3=7) ^[5][4].
• 50% or more of your total biopsy cores contain cancer ^[5][16].

5. High Risk

High-risk prostate cancer has a higher probability of spreading outside the prostate. You are in this group if you have any one of these standard high-risk features:

• Clinical stage T3a (extraprostatic extension) ^[9][10].
• Grade Group 4 or 5 (Gleason score 8, 9, or 10) ^[17][9].
• PSA level strictly greater than 20 ng/mL ^[17][9].

6. Very-High Risk

This category strongly suggests a significant likelihood of local spread or progression. You fall into this group if you have any one of the following criteria:

• Clinical stage T3b or T4 (tumor invading seminal vesicles or nearby structures) ^[10][11].
• A primary Gleason pattern of 5 (the most aggressive cell appearance) ^[17][11].
• More than 4 biopsy cores (meaning 5 or more) that contain Grade Group 4 or 5 cancer (Gleason 8–10) ^[17][11].
• Two or more of the standard high-risk features mentioned in the high-risk section above ^[11][18].

What This Risk Group Does and Does Not Tell You

Your risk group helps organize your treatment options, but it is not the only deciding factor. Age, life expectancy, overall health, genomic testing, and specific pathology features (such as cribriform or intraductal patterns) also influence recommendations.

• Active Surveillance: Often recommended for very-low and low-risk cancers. This is a structured, active monitoring program using regular PSA tests, physical exams, MRIs, and repeat biopsies aiming to detect progression early while preserving quality of life ^[1]. This is different from Watchful Waiting, which is a symptom-focused approach usually chosen when curative treatment is less beneficial due to other major health conditions.
• Active Treatment: Intermediate, high, and very-high-risk categories usually prompt discussions about active treatments. This could mean surgery (radical prostatectomy) or definitive radiation combined with androgen-deprivation therapy (hormone therapy). Treatment is personalized; not every high-risk patient undergoes surgery, and radiation is tailored to individual surgical or biopsy findings.

Seeing a risk label can be frightening. It is entirely reasonable to get a second opinion on your pathology slides or to consult with both a urologist (surgeon) and a radiation oncologist before making a decision.