Grading Your Cancer

One important component of staging your cancer is the grade of the cancer. While the stage of your cancer looks at where the cancer is present in your body—how it is behaving at the macro level—the grade describes what the actual cancer cells look like under a microscope—how they are behaving on a micro level.

Traditionally, prostate cancer grades were described according to the Gleason Score, a system named for the pathologist who developed it in the 1960s. Dr. Donald Gleason realized that cancerous cells fall into 5 distinct patterns as they change from normal cells to tumor cells. The cells are scored on a scale of 1 to 5. Those cells closest to 1 are considered to be “low-grade” tumor cells and tend to look similar to normal cells. Cells closest to 5 are considered “high-grade” and have mutated so much that they barely resemble normal cells.

How is the Gleason Score Derived?

The pathologist looking at the biopsy sample will assign one Gleason grade to the most predominant pattern in your biopsy and a second Gleason grade to the second most predominant pattern. For example: 3 + 4. The two grades will then be added together to determine your Gleason score (between 2 and 10).

What Does it Mean?

Generally speaking, cancers with lower Gleason scores (2–4) tend to be less aggressive, while cancers with higher Gleason scores (7–10) tend to be more aggressive.

It’s also important to know whether any cells rated at Gleason 5 are present, even in just a small amount, and most pathologists will report this. Having any Gleason 5 in your biopsy or prostate puts you at a higher risk of recurrence.

But because many prostate cancer cases are extremely slow-growing, the Gleason system didn’t necessarily do a good job of communicating the risks for these cases. Patients with scores of 6 and 7 didn’t have a clear picture of the nature of their particular cancer.

What is an ISUP Grade Group?

In 2014, the International Society of Urological Pathologists released supplementary guidance and a revised prostate cancer grading system, called the ISUP Grade Groups.

The ISUP Grade Group system is simpler, with just five grades, 1 through 5.

Risk Group ISUP Grade Group Gleason Score
Low Grade Group 1 Gleason Score ≤ 6
Intermediate Favorable Grade Group 2 Gleason Score 7 (3 + 4)
Intermediate Unfavorable Grade Group 3 Gleason Score 7 (4 + 3)
High Grade Group 4 Gleason Score 8
High Grade Group 5 Gleason Score 9-10

Your doctor may report your score as a Gleason Score or an ISUP Grade Group, but you may receive both scores.

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