The Gleason grade uses numbers 1 to 5
Prostate cancer can have several patterns under the microscope, which are each assigned a different number. The first number in the score is the most common and the second number in the score is the next most common pattern seen under the microscope. Once those two numbers are determined, they are added together to come up with the Gleason score, which ranges from 2 to 10.
- If the highest grade takes up 95% or more of a man’s biopsy, that grade is counted twice as the Gleason score
- If three grades of cancer are found in one biopsy core sample, the highest grade is always used, even if the majority of the core sample involves low-grade cancer
- Most biopsies are grade 3 or higher. Grades 1 and 2 are rarely used.
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- Grade 1: The cells look almost like normal cells (called well differentiated) and are uniformly spaced in a tight mass.
- Grade 2: The cancer cells are still well differentiated, but are arranged more loosely, are more irregular in shape, and some cells have spread to other prostatic tissue.
- Grade 3: The cancer is moderately differentiated; cells vary in size from small to large; and more cells have invaded other prostatic tissue.
- Grade 4: The cancer cells are irregular, distorted, and look less like normal cells (called poorly differentiated), and there is considerable spread (called invasion) to other prostatic tissue.
- Grade 5: The cancer cells do not look anything like normal cells and have spread in haphazard “clumps” of all different shapes and sizes through the prostate.
In order to simplify the Gleason scoring system a grade grouping system has been proposed.
- Gleason 6 (3+3=6) – Grade 1
- Gleason 7 (3+4=7) – Grade 2
- Gleason 7 (4+3=7) – Grade 3
- Gleason 8 – Grade 4
- Gleason 9-10 – Grade 5
According to the American Urological Association, the lowest Gleason score that is usually found after a biopsy is 5. The cancer is considered to be more aggressive as the score rises. Scores of 8 to 10 are considered to be the most aggressive, which means that the cancer is more likely to grow and spread more quickly. The biopsy results (called the pathology report) will contain other important information to help the doctor assess how aggressive prostate cancer may be. This includes:
- How many biopsy core samples were positive for cancer
- How much cancer was in each core sample (this is given as a percentage)
- Whether cancer was found in just one side of the prostate gland or in both sides (which is referred to as bilateral)
In order for a doctor to determine prostate cancer staging, a number of tests (bone scan, CT or CAT scan, MRI, or a ProstaScint™ scan) may be ordered to see if the cancer looks like it is:
- Confined only to the prostate (called localized prostate cancer)
- Spreading outside the prostate (called advanced prostate cancer)
Prostate cancer staging (also called the clinical stage) is based on the results of all of a man’s tests, physical exams, and biopsy.
The TNM staging system is the most commonly used system for determining prostate cancer stages.
With the TNM system:
- The “T” stands for the local extent of the primary tumor.
- The “N” represents the presence of metastases (the spread of cancer) to nearby lymph nodes.
- The “M” represents the presence of “distant” metastases to other parts of the body (this means the cancer has traveled in the bloodstream to bony areas, usually the pelvis, ribs, or long bones with prostate cancer).
- Johns Hopkins Medicine FAQs: Prostate Cancer
- Gleason Grade Progression is Uncommon
- Bad Grades for Gleason: A new grading system for prostate carcinoma
- Understanding Your Pathology -- Johns Hopkins FAQ Sheet
- Prostate cancer lives as it is born: slow-growing and benign or fast-growing and dangerous
- Interpreting Your Pathology Report: GLEASON X+Y=Z: Jonathan Epstein of Johns Hopkins
- Prostate Cancer Grading & Prognostic Scoring
- Favorable vs Unfavorable Intermediate-Risk Prostate Cancer: A Review of the New Classification System and Its Impact on Treatment Recommendations
- Current PC Gleason Scoring, Biopsy and AS
- How is prostate cancer staged?