There is no “normal” Gleason score because the Gleason scale only applies to prostate tissue that contains cancer. If your biopsy shows no cancer, you won’t receive a Gleason score at all. The lowest score assigned to a cancer found on biopsy is 6, which represents the least aggressive form of prostate cancer and carries a negligible risk of spreading.
The scale technically runs from 2 to 10, but grades 1 and 2 describe tissue that looks nearly normal and isn’t considered cancerous. In practice, scores below 6 are not used. So when people ask about a “normal” Gleason score, what they usually want to know is: what score means I’m in the best position? That answer is 6.
How the Gleason Score Is Calculated
A pathologist examines your biopsy tissue under a microscope and assigns a grade from 1 to 5 based on how the cancer cells are arranged. Cells that still form recognizable, well-organized glands get lower grades. Cells that have lost their structure and look increasingly chaotic get higher grades.
The pathologist identifies the two most common patterns in the sample. The most dominant pattern is listed first (the primary grade), and the second most common pattern is listed second (the secondary grade). These two numbers are added together to produce the Gleason score. For example, if the most common pattern is grade 3 and the second most common is also grade 3, the score is reported as 3+3=6. If only one pattern is present, it’s counted twice.
This is why the order of the two numbers matters. A score of 3+4=7 means most of the cancer looks relatively well-formed, with a smaller portion that’s more disorganized. A score of 4+3=7 means the opposite: most of the cancer is poorly formed. Both add up to 7, but they are not the same diagnosis.
Why Gleason 6 Is Considered Low Risk
Gleason 6 (3+3) is the most commonly diagnosed prostate cancer among men who are screened with a PSA test. It is the most well-differentiated type, meaning the cells still closely resemble normal prostate tissue. In a review of 14,000 surgical specimens using the updated grading system, not a single case of Gleason 6 cancer had spread to the lymph nodes. A separate long-term study following men with confirmed Gleason 6 disease found no lethal prostate cancers over more than 2,200 person-years of follow-up.
Because of this extremely favorable outlook, active surveillance is the recommended approach for most men with Gleason 6 cancer. That means regular monitoring with PSA tests, repeat biopsies, and sometimes MRI rather than immediate treatment. Major guidelines from organizations including the American Urological Association, the NCCN, and European Association of Urology all endorse this approach for Gleason 6 without other risk factors.
Gleason 7: The Score Where Details Matter Most
A Gleason score of 7 falls into intermediate risk territory, but the two versions of 7 behave quite differently. Men with 4+3=7 on a surgical specimen are about three times more likely to develop lethal prostate cancer compared to men with 3+4=7. In biopsy data, the gap is even more striking: cancer mortality rates were roughly four times higher for 4+3 compared to 3+4. Ignoring which pattern dominates can obscure critical information about how a cancer will behave.
Some men with Gleason 3+4=7 may still be candidates for active surveillance, provided they meet additional criteria: low PSA (under 10), a small number of positive biopsy cores, low volume of the more aggressive pattern, and early clinical stage. Guidelines vary on the exact thresholds, but all agree that favorable features need to be present across the board. If the grade 4 component has a specific structural pattern called cribriform architecture, European guidelines recommend against surveillance because this pattern is linked to worse outcomes.
Gleason 8 Through 10: High-Grade Cancer
Scores of 8, 9, and 10 represent high-grade prostate cancer with increasingly aggressive characteristics. Even within this range, outcomes are not identical. Gleason 9 and 10 cancers are significantly more aggressive than Gleason 8, with higher rates of spread to the nerves surrounding the prostate, extension beyond the prostate capsule, and metastasis to bone and other organs at the time of diagnosis.
These cancers are composed of cells that have largely or completely lost their glandular structure. Treatment for high-grade prostate cancer is typically more aggressive and may involve combinations of surgery, radiation, and hormonal therapy.
The Grade Group System
In recent years, a newer classification system has been adopted alongside the traditional Gleason score to make results easier to understand. Developed from a study of more than 25,000 prostate cancer cases, it divides cancers into five Grade Groups:
- Grade Group 1: Gleason 6 or lower
- Grade Group 2: Gleason 3+4=7
- Grade Group 3: Gleason 4+3=7
- Grade Group 4: Gleason 8
- Grade Group 5: Gleason 9 or 10
One advantage of this system is psychological. Under the old Gleason scale, being told you have a “6 out of 10” can sound like you’re already in the middle of a dangerous range. Under the Grade Group system, that same cancer is Grade Group 1 out of 5, which more accurately conveys that it sits at the lowest end of the risk spectrum. Your pathology report will typically include both the Gleason score and the Grade Group.
What Else Appears on Your Pathology Report
The Gleason score is the most well-known number on a prostate biopsy report, but it’s not the only one that matters. Your report will also include how many of the biopsy cores contained cancer and the percentage of each core that was involved. A single core with a small amount of Gleason 6 cancer is a very different situation from multiple cores heavily involved with the same score.
Pathologists also note whether cancer has invaded the nerves (perineural invasion), whether it extends into the fat surrounding the prostate, and whether certain high-risk structural patterns are present. For cancers above Grade Group 1, the percentage of the higher-grade component is documented because it influences prognosis and can factor into treatment decisions. All of these details work together with the Gleason score to build a complete picture of risk.
Tertiary Patterns and Hidden Risk
Sometimes a biopsy or surgical specimen contains a small amount of a third, more aggressive pattern beyond the two used to calculate the Gleason score. This is called a tertiary pattern. If the dominant patterns are 3 and 4 but there’s a tiny amount of pattern 5, that third component doesn’t change the official Gleason score. However, cancers with a tertiary higher-grade pattern have been associated with higher rates of cancer recurrence after surgery compared to cancers with the same Gleason score but no tertiary pattern.
Most pathologists (89% in a recent survey) do not change the Grade Group based on a tertiary pattern, but nearly all will note it in the report. If your report mentions a tertiary pattern 5, it’s worth discussing with your urologist, as it may influence how closely your cancer is monitored or whether surveillance remains appropriate.