Study: DRE exhibits low diagnostic value in prostate cancer detection

Commentary
Video

“It seems that DRE does not add a clinically or statistically significant [benefit] to PSA testing alone in detecting prostate cancer,” says Shahrokh F. Shariat, MD.

In this video, Shahrokh F. Shariat, MD, shares key findings from 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 main aim was to assess the diagnostic value of the rectal exam and PSA, both of them alone and in combination, in screening for early prostate cancer. That's the setting. We have to understand we were looking at [the] early detection and screening setting; these were the studies that we included. So, we did not include, [if] your patient [is] coming to you and has symptoms. That is very important. After a very complex literature search, we came down to 8 studies that we felt had high enough quality of data and met the inclusion criteria to be included, with 85,700 patients approximately that we could include in our analysis, which is pretty large study. From those, there were 3 randomized control trials. We know all 3, the ERSPC [and] the PLCO being part of the 3 randomized trials. There were 5 prospective diagnostic studies with 26,000 [patients]. But the large majority, 60,000, approximately were from randomized controlled trial. These were the patients.

If we look at the diagnostic accuracy for prostate detection tools, we found no difference between DRE, the digital rectal exam, and PSA, or any type of combination between those 2, in the positive predictive value domains. If one is positive, you will have cancer. We find no difference. Even if you combine them, [there was] no added value of one to the other one in either way you looked at. The key end point that we thought is the most important is the cancer detection rate. The cancer detection rate means, what is the likelihood of this test actually leading to a cancer, not this positive predictive value, if the test is positive, do you have cancer. So, it's a different question and it's a more relevant question in the screening setting, I think, because you also want to know if it is negative, are you safe? Or are you likely not to have cancer at this moment that matters, because you have also some longitudinal follow. In that setting, we found that PSA performed significantly better–statistically significant, but also clinically significant benefit–than the rectal exam in the cancer detection rate. Moreover, adding DRE to the PSA did not improve our cancer detection rate. That is very important. PSA alone outperformed or performed as good as if you add a DRE.

We looked at it in many ways, in many combinations, all permutations that are possible. We actually broke it down by each clinical trial. [We asked in] each study that we looked at, did you find it? Is it a trend? We found that it's pretty consistent across all the studies, but specifically, the magnitude of value of DRE seems to decrease across time. As you are getting more uptake of patients going for some form of early detection, be it organized or non-organized, depending on the country evaluating. We also looked at the bias of the trials. If you have a study, you can have some design bias, and so it is a complex analysis. We found some minimal to moderate bias in some of trials, most of them didn't have it. So, it's not like the studies were designed to give a benefit to one test or to the other one or the population in any certain way.

Our conclusion based on that was, the DRE is not performing as good as often expected or valued in any detection tool. I think today, we would not have DRE as a standard test, we would not include it in any test, we would not add it to anything. PSA alone seems to be sufficient for early detection and screening, leading to further testing. So, it's not the end and that often ends up with further testing, could be the MRI, MRI plus DRE, or whatever. That we didn't ask; that wasn't the purpose. We have another systemic trial evaluating that, of the MRI first [on] assessment. And obviously, if you have clinical signs or symptoms that you probably will undergo a DRE. It seems that DRE does not add a clinically or statistically significant [benefit] to PSA testing alone in detecting prostate cancer.

This transcription has been edited for clarity.

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