What is a Gleason Score? Grading System for Prostate Cancer

What is a Gleason score?

A Gleason score is a crucial tool in assessing prostate cancer. It helps doctors understand how aggressive your cancer might be, which is essential for determining the best treatment approach. Named after Dr. Donald Gleason, who developed the system in the 1960s, this score is based on how your prostate cancer cells look under a microscope.

Think of the Gleason score as a snapshot of cancer cells on a microscope slide. Like a photograph of cars on a freeway, it shows where the cancer cells are at a moment in time, but it doesn’t tell us how fast they’re moving. This is where more advanced tools become crucial.

The Gleason score has been a cornerstone of prostate cancer diagnosis and treatment planning for over half a century. Its enduring use is a testament to its value in cancer assessment. However, sole reliance on Gleason scores can sometimes lead to under or overtreatment, highlighting the need for more accurate and personalized tools.

Advanced genetic tests like Prolaris go beyond the snapshot. They’re like looking at each car’s speedometer or examining its engine. These tests assess the activity of certain genes to predict cancer aggressiveness and potential outcomes more accurately. By providing insight into how quickly the cancer might spread, they help doctors and patients make more informed decisions about treatment options.

Over the years, the scoring system has been refined and updated to improve its accuracy and usefulness. Today, it’s used in conjunction with other advanced diagnostic tools to provide a more complete picture of a patient’s prostate cancer.

For example, imaging studies such as multiparametric MRI can provide detailed visualizations of the prostate, aiding in targeted biopsies and treatment planning. By combining these various tools with genetic testing, doctors can make more personalized and informed decisions about patient care, potentially leading to better outcomes and reducing the risk of overtreatment.

How are Gleason scores calculated?

Pathologists review biopsy tissue and assign it a Gleason grade based on the appearance of the cells. If cancer is present, it will be assigned two Gleason grades ranging from 1 to 5. The primary grade, or first number shown, is the most common Gleason pattern (grade) found in the biopsy. The second number is the second most common Gleason pattern (grade). These two numbers are added together for a Gleason score. Gleason scores range from 2 to 10 with most prostate cancer ranging from 6 to 10.

An example Gleason score is 3+4=7. In this example, 3 is the primary pattern, and 4 is the secondary. When added together, they equal 7.

What Are Grade Groups?

Another term you may hear regarding Gleason scores is Grade Groups. Gleason scores have been divided into groups ranging from 1 to 5. Gleason score and Gleason grades determine the Gleason group.

Gleason Group Break Down

Grade group 1: Gleason score = 6 (or less) and Gleason pattern = 3+3

Grade group 2: Gleason score = 7 and Gleason pattern = 3+4

Grade group 3: Gleason score = 7 and Gleason pattern = 4+3

Grade group 4: Gleason score = 8 and Gleason pattern = 4+4, 3+5, 5+3

Grade group 5: Gleason score = 9 or 10 and Gleason pattern = 4+5, 5+4, 5+5

What’s a Normal Gleason Score?

It’s important to understand that there isn’t a “normal” Gleason score for a healthy prostate. Gleason scores are only assigned when cancer is present in a prostate biopsy. If no cancer is found, no Gleason score is given. In other words, a truly healthy prostate doesn’t have a Gleason score at all.

What is a Good Gleason Score?

In the context of prostate cancer, a “good” Gleason score is generally considered to be on the lower end of the scale. A Gleason score of 6 (3+3) is the lowest score typically given for prostate cancer found on a biopsy. This score, which corresponds to Grade Group 1, suggests a low-grade or less aggressive form of cancer.

However, it’s crucial to remember that even a Gleason score of 6 still indicates the presence of cancer. While it may be less likely to grow and spread quickly, it still requires careful monitoring and discussion with your doctor about the best approach to treatment or active surveillance.

What is a Bad Gleason Score?

Higher Gleason scores suggest more aggressive or advanced prostate cancer. Scores of 8, 9, or 10 (Grade Groups 4 and 5) are generally considered “bad” or high-risk. These scores indicate that the cancer cells look very different from normal cells and the cancer is likely to grow and spread more quickly.

A Gleason score of 7 falls in the middle. It can be either 3+4=7 (Grade Group 2) or 4+3=7 (Grade Group 3), with the latter considered slightly more aggressive because more of the tumor is composed of poorly differentiated cells.

Remember, while the Gleason score is an important factor, it’s not the only one used to assess your prostate cancer. Your doctor will consider other factors like understanding your PSA level, the stage of the cancer, and your overall health. However, these traditional measures alone can’t always determine if a man is truly safe for active surveillance or if treatment is necessary. This is where personalized genomic tests like Prolaris shine. Prolaris can definitively determine if a man is safe for active surveillance or if they need treatment, and importantly, how much treatment is required. By providing a more comprehensive understanding of your cancer’s behavior, Prolaris helps cut out sole reliance on traditional measures like Gleason score and PSA. This allows your doctor to tailor your treatment plan, ensuring you receive the right amount of treatment for the best possible outcome, whether that includes active surveillance, ADT for prostate cancer, or other treatment options.

Limitations of Gleason Scoring:

While Gleason scores play a vital role in prostate cancer assessment, it’s crucial to understand their limitations. The subjective nature of Gleason grading can lead to significant variability in results:

• Biopsy vs. Surgical Discrepancies: Studies have shown that Gleason scores from biopsies match those from removed prostates only about 45% of the time. This discrepancy means that many men may be undergoing unnecessary surgeries based on inaccurate initial assessments.
• Pathologist Variability: Gleason grading and scoring are largely subjective, and not all pathologists may agree on a Gleason grade, especially on small tissue samples obtained at biopsy. This can lead to varying interpretations of the same sample.
• Limited Sampling: Biopsies only examine a small portion of the prostate, potentially missing areas of higher-grade cancer or overestimating the grade based on a small area of aggressive cells.

Given these limitations, it’s clear that patients need more comprehensive information to make informed decisions about their treatment. Advanced genomic tests can provide additional insights into cancer behavior, helping to create a more accurate and personalized treatment plan. These tests can help reduce the risk of overtreatment based solely on potentially inaccurate Gleason scores, ensuring that each patient receives the most appropriate care for their specific situation.