Now, what does the cancer look like under the microscope? Are the cells well differentiated, or are they poorly differentiated? The architecture of normal, well-differentiated cells involves distinct, clearly defined borders. Well-differentiated cells have clear centers—think of tiny round doughnuts. When cancer cells become poorly differentiated, they seem to melt together and form solid, nasty blobs of malignancy. These cancers are the most aggressive. They run rampant, sweeping through nearby tissue and launching missiles to distant sites in the body, no longer respecting boundaries—their own, or other cells’. The results are often devastating; the fastest, most out-of-control cancer cells can kill a man within a year of their initial clinical presentation. Well-differentiated cancers tend to progress very slowly, and poorly differentiated cancers tend to spread like wildfire.
Pathologists use a system called the Gleason score to rank cell differentiation. Basically, a low Gleason score—2,3,4—is good. A high Gleason score— 8,9,10—is not. What about a score right in the middle? This is another murky area, where it’s hard to predict what course the cells will take.
Scientists have shown that cancers with a high Gleason score are more likely to be “margin-positive” (to have cancer that has penetrated the prostate wall to a point where it can’t all be removed in surgery), more likely to have cancer in the seminal vesicles, and more likely to defy treatment than cancers with a lower score. With a higher Gleason score, there’s also a higher likelihood of cancer spreading to the lymph nodes. Therefore, if a man has a high Gleason score, there is a good probability that his cancer has spread beyond the prostate wall and maybe to nearby structures.
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