Dr. Shariat discusses the background of a study comparing DRE and PSA


"Many men are quite reluctant to go to a specialist, specifically the urologist, because of the fear or reluctance to undergo an invasive test, [such as] a rectal exam," says Shahrokh F. Shariat, MD.

In this video, Shahrokh F. Shariat, MD, shares the rationale for the study, “Comparing the Performance of Digital Rectal Examination and Prostate-specific Antigen as a Screening Test for Prostate Cancer: A Systematic Review and Meta-analysis.” Shariat is chairman and professor of urology at the Medical University of Vienna in Vienna, Austria, as well as the deputy head of the Comprehensive Cancer Center.

Video Transcript:

The way that prostate cancer early detection screening has happened historically, PSA was introduced slowly in early 90s, and increased in value and understanding how we're going to use PSA. We all realize PSA is a tremendous biomarker, probably the best one in oncology. But it is not cancer-specific, it's just prostate-specific. It could be falsely elevated. We started using it in early detection and screening studies, and [we] had a multitude of well-designed, screening trials that were positive and show that PSA screening improves cancer-specific survival and overall survival. Nevertheless, it leads to overdiagnosis and potentially overtreatment. [But] it adds a lot of value.

So, the early studies on prostate cancer screening strategies actually showed us that the digital rectal exam, which was the tool urologists used not only to assess if there is an abnormality on the prostate, but also the size of the prostate, and often also, if there are symptoms associated with it, like for a screening setting. These were our 2 tools for the early detection screening. With the smarter use of PSA and the more widely use of PSA and the earlier patients go to screening, I think we all felt in a clinical setting that the rectal exam as a screening tool was decreasing in predictive value and also in negative predictive value, and also the cancer detection rate. So, that was one thing. We felt that the rectal exam is not adding as much. This was the clinical experience of many of my colleagues and experts around the world.

Number 2, I think today we have a new paradigms where a lot of information that we gained through a rectal examination will be gained through a multiparametric MRI that is done if the PSA is in abnormal range. That is the second thing.

The third thing, I think we also have shifted in our understanding of not only detecting cancer, but detecting those clinically significant cancers. That has also showed up in our PSA range. We don't have to get for all the cancers; we need to go for those that will be clinically significant. If we detect them a little bit later, maybe it doesn't matter in our management strategies.

The fourth point is the clinical reality that we're facing in the practice of managing our patients. That is that many men are quite reluctant to go to a specialist, specifically the urologist, because of the fear or reluctance to undergo an invasive test, [such as] a rectal exam. Now, [as] urologists, we don't think that is that invasive; it's part of our normal armamentarium to examine the patient and should continue to be. Is [that rectal exam] really necessary for the detection of prostate cancer? That's the question. And, if that is a roadblock for patients to come for their management or early assessment, if they're at risk for prostate cancer or whether they have prostate cancer, can we can we eliminate that test if it's of no value? Or should we include it? These were the questions we have.

So, all those rationale brought us to the point of asking if we look at all the literature of high quality data–and that is the challenge, of randomized controlled trials or prospectively run detection trials studies–if we look and put all the data together, even if we include the older studies that maybe overvalued the rectal examination, because we were really assessing a broad pool of patients. That is not the same case today. What is the value of the digital rectal examination? How much does it add to PSA for the cancer detection rate and for the positive predictive value of saying it's abnormal, you need to move further along in your diagnostic paradigm. That was the question we asked in a specific setting.

Now, what did we use to answer that question, we used all the data that was out there from the prospective trials, high-quality trials. We used stringent criteria, which study could be included, which one could not be included, that you can read in the paper. We also assessed the bias of those trials. How much does it affect the outcome? Even if you have a prospective detection study or trial, you could have a bias inherent to it. How much does it weigh? And we did a systematic review and meta-analysis, and then a meta-regression analysis, so that we can really compare the different settings and adjust for the differences to understand the value of those diagnostic tools.

This transcription has been edited for clarity.

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