The Debate on Prostate Cancer Grading: Addressing Underdiagnosis and Overdiagnosis Concerns "Presentation" - Andrew Vickers

July 24, 2024

At the CAncer or Not Cancer: Evaluating and Reconsidering GG1 prostate cancer (CANCER-GG1?) Symposium, Andrew Vickers addresses concerns about underdiagnosing low-volume Grade Group 2 prostate cancer when considering reclassification of Grade Group 1. He argues that many objections to redesignation are speculative and fail to consider the current problems of overdiagnosis, overtreatment, and patient anxiety. Dr. Vickers concludes by emphasizing the need to shift attention towards the volume of pattern 4 cancer as the primary concern in prostate cancer diagnosis and management.

Biographies:

Andrew Vickers, Attending Research Methodologist, Department of Epidemiology & Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY


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Speaker 1: How concerned should we be about underdiagnosing low-volume Grade Group 2?

Andrew Vickers: Okay, so one of the things that frustrates me about trying to change things is the defenders of the status quo say, "Well, we just need to come up with arguments against changing and then we are done." Well, if we got off our penny-farthings and got on racing bikes, well we'd have to buy new shoes and we'd have to buy new bottles. It's never that. It's always a balance of harms and benefits.

I find, personally, a lot of the arguments against redesignation are purely speculative. They're "what ifs." We have this massive problem we have right now with overdiagnosis, with overtreatment, with patients getting very anxious, which extends to suicide, right? But, well, speculatively, what if? And this is one of the what ifs. If we call pattern 3 not cancer, there may be pathologists, when they're not sure, they're going to call pattern 3, pattern 4, and if this happened that somewhere in the future we are going to get these great active surveillance rates for pattern 3, that means that changing the name of pattern 3 to not cancer would actually decrease active surveillance rates. Pure speculation.

Let's look at the actual evidence. This was a paper I did with Behfar Edhaie and Samson Fine, who's on this call, and we just looked at systematic biopsies in men who were Grade Group 2. So what you have on the X-axis is how much pattern 4 you had and on the Y-axis it is a metric of oncologic aggressiveness. Now, we have one for BCR as well, but in this particular graph, it's adverse pathology. And the black line shows you that as you get more and more pattern 4, more millimeters of pattern 4 on biopsy, your risk goes up. The great gray line there is your risk if you have pattern 3 only, so Grade Group 1. What you can see is that if you have less than 1 or 2 millimeters of pattern 4, that is the same risk of pattern 3. And those men we can put on active surveillance.

This is what we currently have to tell men who have low-volume pattern 4 to get them on active surveillance. It's a total word salad of, "you don't have the lowest risk, but it's kind of the lowest risk. But it's not. You don't have very much." Wouldn't it be much simpler if we could just say this, "You do have cancer, but only a very, very small amount. In fact, it's so small we can just watch it, treating it as it starts to grow too big." So I have no doubt that redesignating cancer would reduce overdiagnosis.

Here's my question. This is the biggest problem we have: pattern 4. Currently, we look at the ratio between pattern 4 and pattern 3. Pattern 3 is indolent, so I just don't understand why the ratio matters. We really have to start looking at the absolute volume of pattern 4. And that's the end of my talk.