Digital rectal exam fails as a screening tool for prostate cancer

Digital rectal examination (DRE) is neither helpful nor useful as a solitary screening tool for prostate cancer in middle-aged men, say researchers reporting the PROBASE study.

The study compared risk-adjusted screening measures in men who had prostate-specific antigen (PSA) measured at age 45 with those who had PSA plus DRE measurements at age 50.

The results show that as a solitary screening tool, 99% of EDRs did not raise suspicion of prostate cancer, and of the 57 cases where DRE did raise suspicion, only three men were found with cancer, all low-grade, reported Agne Krilaviciute, PhD, of the German Cancer Research Center in Heidelberg, and colleagues.

“We also find that the rate of cancer detection by PSA is four times higher than that of DRE detection. About 18% of tumors are located in the part of the prostate where DRE cannot detect them,” he said. she stated during an oral presentation here at European Urological Association (UAE) Congress.

The researchers found that the majority of prostate cancers that occurred in this relatively young population were Grade 1 (Gleason score 3+3=6) or Grade 2 (Gleason score 3+4=7) from the International Society of Pathology urology (ISUP). DRE only yields positive results in about 12% of ISUP grade 1 or 2 cases, they noted.

“We conclude that digital rectal examination as a solitary screening test does not lead to a significant PCa [prostate cancer] detection rate in young men,” Krilaviciute said.

Fall by the wayside

The study adds to the growing body of evidence that the DRE may not be particularly useful as a screening tool or when used in the active surveillance of men with prostate cancer.

As recently reported by Medscape Medical Newsan international consensus panel found that DRE can be safely ignored for active surveillance when MRI and other more accurate and objective measurements, such as biomarkers, are available.

A prostate cancer expert who was not involved in the PROBASE study said Medscape Medical News that when he was in medical school, it would have been considered a serious breach of practice not perform a DRE, but that things have changed considerably over the past few years.

“We now have PSA, we have the technology with MRI, and the yield from digital rectal examination is very low,” commented Julio Pow-Sang, MD, head of the genitourinary oncology program at Moffitt Cancer. Center in Tampa, Florida,

“Empirically, it’s very rare to find positive cancer by rectal exam around the time of PSA,” he said, adding that the exam itself is very subjective, with varying results depending on skill. of the particular examiner.

“I think over time, with good studies like this, digital rectal examination specifically for prostate cancer will slowly fade away,” Pow-Sang said.

PROBASE Results

PROBASE was a randomized screening study recruiting 45-year-old men to test a risk-adapted screening strategy using a baseline PSA value with the additional offer of rectal examination in a large subcohort of participants.

The study was conducted in Germany, and the authors note that “the German Statutory Early Detection Program recommends digital rectal examination as a stand-alone screening test beginning annually at age 45.”

PROBASE investigators recruited 46,495 men from February 2014 to December 2019.

Of the first 23,194 men enrolled, 6,537 underwent a rectal examination at enrollment without a PSA test in the study.

In this group, 6480 DREs (99%) were not suspected of cancer and 57 (1%) were. Of those suspected of prostate cancer, 37 underwent a biopsy and 20 did not. Of those biopsied, only two were found to have prostate cancer. This translated into a cancer detection rate of 0.03% for digital rectal examination.

After a median of 6.6 years of follow-up, only one additional case of ISUP grade 2 prostate cancer was detected among the 6,357 men who had a digital rectal examination at enrollment, which translated into a prostate cancer detection rate of 0.05%.

Investigators also examined men who initially suspected DRE results. They assumed that a tumor detectable by DRE at age 45 would still be evident 5 years later and should be detectable by PSA at age 50. Of the 57 men with initially suspicious results, 11 returned for PSA screening but declined biopsy, and of these only one had an elevated PSA level. He then underwent a biopsy, but the results were negative.

Of those who underwent biopsy based on digital rectal examination, 16 had prostatitis, 14 had benign prostatic hyperplasia, one had high-grade prostatic intraepithelial neoplasia, one had atypical small acinar proliferation, and three had equivocal results.

In total, investigators found 24 tumors in the men screened with DRE. Of these, three occurred in men with results deemed suspicious and 21 in men with non-suspicious digital exams. All tumors were ISUP grade 1, 2 or 3 tumors.

Among 245 men who underwent biopsies for PSA ≥ 3 ng/mL, primarily Prostate Imaging Reporting and Data System (PI-RADS) 3-5 tumors, ERD results at the time of biopsy were not not suspicious in about 82% of cases, Krilaviciute said.

“We also used the MRI data to determine what proportion of tumors would be potentially detectable by DRE. We estimated that approximately 18% of tumors are located in the upper part of the prostate, which is not detectable by DRE”, she said. “Even excluding these tumors, the DRE detection rate is still low in palpable tumors.”

Although ERD performed better in higher grade tumours, 80% of PROBASE participants’ tumors were ISUP grade 1 or 2 and were likely to be missed by ERD, a- she added.

“In Germany, the recommendations for screening still include people aged 45 for an annual digital rectal examination. The PROBASE trial allowed us to assess for the first time what the diagnostic performance of digital rectal examination was at such a young age, and we see that 99% of men having digital rectal examinations have suspicious findings, and among the 1% with suspicious findings are extremely unlikely cancers,” she said.

The study was supported by Deutsche Krebshilfe (German Cancer Aid). Krilaviciute and Pow-Sang have declared that they have no relevant conflict of interest.

Annual Congress of the European Association of Urology (EAU 2023). Abstract A0899. Presented March 9, 2023.

Neil Osterweil, award-winning medical journalist, is a longtime and frequent contributor to Medscape.

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