Epidemiology For Dummies
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When men who have prostate cancer talk to each other, they sometimes exchange their Gleason scores or their cancer stages with an intensity that two combat veterans might use when exchanging the name of a battle they both served in. They say such things as "I'm a Gleason 6," or maybe "I'm a Gleason 4" — rather than saying that they were at the battle of Khe San in Vietnam or in the Gulf War. This new prostate cancer identity is now more important than where these cancer veterans are from, how much money they make, or even what type of job they have. Cancer trumps everything.

"So what is the Gleason score, and how does it work?" you ask. Read on!

Getting the scoop on the score

The Gleason score was invented in 1966 by Dr. Donald Gleason, a pathologist. He based the score on information derived from studies of the biopsies of nearly 3,000 patients who had been diagnosed with prostate cancer. Pathologists worldwide rely on the Gleason score. The score provides an effective measurement that helps your doctor determine how severe your prostate cancer is, based on the appearance of the cancer cells when viewed under a microscope. All cancer looks abnormal to a pathologist, but low-grade cancers have cells that often look similar to healthy cells from the gland or organ that has been affected by the cancer. As a result, the pathologist can recognize that she's looking at prostate cells under the microscope. But when the cancer is aggressive, the cancer cells look less and less like normal prostate cells (or any other kind of cells).

Pathologists find the Gleason grading system to be very reliable. For example, if the Gleason score indicates that the cancer is an intermediate risk cancer (a Gleason score of 7) it nearly always is an intermediate risk. As a result, doctors can make predictions from Gleason grades. The more distorted and aggressive the cancer looks, the higher the Gleason grade, and the more aggressive the cancer behaves in the body.

Understanding how it works

The lowest number on the Gleason grade scale is 1, and the highest is 5. Two Gleason grade numbers are actually determined and then added up to get the final Gleason score.

Here's how it works: The pathologist looks at the biopsied tissue samples through a microscope to determine where the cancer is the most prominent (the primary grade) and then where it's next most prominent (the secondary grade). Next, he assigns a score from 1 to 5 to each area: one score for the primary grade and one score for the secondary grade. The Gleason score is the sum of the primary and secondary grades. As a result, the total score can be anything from a 2 (1 + 1) to a 10 (5 + 5).

Interpreting the results

The lower the score, the better. A combined Gleason score of 10 is very bad (although there are still many treatments that doctors can offer men with high Gleason scores). Here's how the scores break down:

  • Scores from 2 to 4 are very low on the cancer aggression scale.
  • Scores from 5 to 6 are mildly aggressive.
  • A score of 7 indicates that the cancer is moderately aggressive.
  • Scores from 8 to 10 indicate that the cancer is highly aggressive.

Here's a tricky little feature of the Gleason score for you to keep in mind: The Gleason score usually is reported with the primary cancer number given first, and the secondary cancer number reported second. For example, if Jack Sprat's Gleason score is reported as a 4 + 3 = 7, the primary cancer number is a 4, and the secondary cancer number is a 3. Add them up, and they equal a total Gleason score of 7. But remember, not all Gleason scores are equal.

It may sound strange, but if the pathologist classifies Clark Kent with Gleason scale numbers of 3 and 4, which gives him a Gleason total score of 7, Clark is actually in a little better shape, cancerwise, than Jack. Here's why: When the primary grade (the first number) is 3, it means that the cancer has not advanced as far with cellular deterioration as cancer with a primary grade of 4 (such as is the case with Jack's score). Even though their total scores still equal 7, Jack and Clark's Gleason scores aren't exactly the same.

So if you want to know the real deal on your Gleason score, get a breakdown of the two numbers that comprise the score. Ask your doctor for your Gleason score, starting with the primary grade first, followed by the secondary grade and then the total.

The Gleason score from the prostate biopsy (which is just a few slivers of tissue from the cancer) may not be exactly the same as the score the pathologist calculates after surgery, when he's able to look at all the cancer in the entire prostate. Sometimes the score goes up a little, and sometimes it goes down a little.

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