Ask the Experts #4: If I Have a Gleason Score 6 on my Prostate Biopsy, Will it Stay a 6?

In our Ask the Experts series, we’ll put a common question to one of the Grace Prostate Cancer Centre’s urologists, and they’ll offer up an honest, candid response. 

Today, we ask Bay of Plenty Urologist Jim Duthie for his thoughts on the following question:

If I Have a Gleason Score 6 on my Prostate Biopsy, Will it Stay a 6?

This is a trickier question than it seems!

If we start with Gleason 6 prostate cancer on its own, it seems that 6 does not “turn aggressive” and upgrade to a higher number.

Gleason 6 seems to behave in a pretty lazy, indolent way; not spreading through the body or becoming lethal. There is a big “however” about this statement though.

We can never give a solid-gold guarantee that there is no other, more aggressive prostate cancer that has been missed on the biopsy. We can be reasonably confident that if there is a very small amount of low-grade disease, with a normal finger examination, and a reasonably low PSA blood test that it is very unlikely that we are missing a more aggressive cancer.

In this situation, the odds are so favourable that Active Surveillance may be appropriate in selected men. There is definitely an increasing risk of missing higher-grade cancer with an increasing amount of Gleason 6 disease on biopsy.

It seems from the research that a large amount of Gleason 6 can be a marker for more aggressive cancer. In fact, between 20-25% of prostates surgically removed will have higher-grade cancer than was found on the original biopsy.

Think of it like this: you catch a mouse in a trap, reset the trap, and never see another mouse. You never see any droppings or chewed cereal boxes. You probably don’t have rats. But if you have hundreds of mice, everything is getting chewed, you hear scuttling noises in the ceiling, you may well have some rats that you just haven’t seen yet.

So to answer the question, Gleason 6 probably won’t become higher-grade cancer, but a large amount can indicate co-existing cancer that the biopsy did not pick up.

See previous Ask the Expert question and answer posts: 

Does Fish Oil Increase the Risk of Prostate Cancer?

Will I Ever Be Dry Again After Prostate Cancer Treatment?

Will My Ejaculate Change After Prostate Cancer Surgery?

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