With a biopsy we have up to 14 very fine samples.
These are taken systematically throughout the prostate and we send these off to the pathologist.
The pathologist then looks at these under a microscope.
What the pathologist does is look at the glandular pattern in prostate cancer, unlike other cancers where they look at the cells and look at the abnormalities within the cell, with prostate cancer we look at the pattern, the glandular pattern.
So what we do is we look at the most active or predominant cancer that’s present and then we look at the second most predominant pattern.
So there was a pathologist called Gleeson, he determined this grading system.1
So the first Gleeson grade would be out of 5 and the pathologist looks at the most predominant pattern and grades it between 0 and 5.
So for example if it’s very poorly differentiated with the glands being very irregular you might have a score of 4 out of 5.
If it’s very well differentiated it might be 2 or 3 out of 5.
So the pathologist will look at the most predominant pattern, the second most predominant pattern and add them together, and we then a Gleeson sum out of 10.
So for example you might have a Gleeson 4 which is a predominant pattern 4 out 5.
The second most predominant pattern might be 3 out of 5, so that will add up to 4 plus 3 equals 7 out of 10.
So hence people will refer to that as a Gleeson 7 cancer.
The importance of this is that the Gleeson grading gives us an idea of the activeness or aggressiveness of the cancer.2
From this we can tell the natural history.
So if we have someone with a very low Gleeson grade and a low volume of cancer we may elect to monitor that patient, maybe that cancer is not something that’s going to cause them a problem.
If we have someone with a high grade cancer we will elect to treat that patient because that cancer is going to be a threat to that patient.
So that’s the Gleeson grading system.
The other important things with a biopsy is the percentage core positivity.
So they will describe with each core how much cancer affects that core, between 0 and 100% and that’s very important because it gives us an idea of the volume, also the number of cores.
So if you have 14 cores it’s far more important if you had for example 12 out of 14 cores rather than 1 out of the 14 cores.
There are some other things also that we utilise such as perineural invasion and vascular invasion but they’re a bit debatable but they do give us some additional information.
So really if someone has a PSA elevation or a digital abnormality the important thing in my, I believe the important thing is to get a biopsy, get the Gleeson scoring done and then we can accurately tell patients their outcomes from that tumour.
Is it safe to observe it, should that be treated.
So it’s a very, very important part of the assessment for a patient.
References
1. The evolving Gleason grading system - Ni Chen and Qiao Zhou https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4779758/