Dr. Vickers on quantifying Gleason pattern 4 in prostate cancer

In this video, Andrew J. Vickers, PhD, discusses the key take-home messages from the study, “Amount of Gleason Pattern 3 Is Not Predictive of Risk in Grade Group 2–4 Prostate Cancer,” for which he served as the lead author. Vickers is an attending research methodologist in the department of epidemiology and biostatistics at Memorial Sloan Kettering Cancer Center in New York, New York.

Video Transcript:

The difficult thing about saying, "Okay, here's how we should practice" is that we haven't actually come up with an agreed way of quantifying 4. So, different pathologists will do it in different ways. In one of our studies, we actually saw quite big differences between the way that pathologists did it at the University of Chicago vs the pathologists at the University of California, San Francisco. The big takeaway is we need research on the best way to quantify pattern 4. We need to come up with the rules for doing that, because pathologists are doing it in quite different ways. And that's understandable. This has not been an important part of their practice; what they needed to do was get the ratios right. That's the main research takeaway, and I really do think that's an urgent thing, that we should be doing research.

In terms of practice, it's difficult to draw practice conclusions saying treat your men based on the amount of pattern 4, because we don't know the right way of quantifying it. I would just say that urologists should be focusing much more on the total amount of pattern 4, if they have that information available, than on the ratio of pattern 3 and 4, and therefore the grade group. I think one particular area is for active surveillance. Particularly in patients with great group 2, should men with grade group 2 go on active surveillance. I think what you want to look at is the is the total amount of pattern 4. In a separate paper, we give a very specific example of this. It was 2 men both with grade group 2 who were followed on active surveillance. One had a massive increase in the amount of 4; it went from something like 0.7 millimeters to 10 millimeters of pattern 4, but because the amount of pattern 3 also increased, that man was not upgraded. It's typical thing we worry about, [being] upgraded. There was another man who had a very tiny increase in his amount of pattern 4, from something like 0.6 millimeters to 0.8 or something like that. But because the amount of patent 3 went down, that patient was upgraded. I think that gives you an example of how thinking about this in very black and white terms of upgrading as being the problem. Whereas I think we really need to focus in terms of eligibility for active surveillance in terms of absolute length of pattern 4.

This transcription has been edited for clarity.