PSA Testing Found More Prostate Cancers Than the Rectal Exam

CATEGORY: MEN’S HEALTH

Guidelines still pair the rectal exam with the PSA blood test, so the obvious question is what the exam adds. Eight studies covering 85,798 screened men were pooled to answer it. The blood test detected roughly three times as many prostate cancers as the finger exam, and adding the exam on top of the blood test found no more.¹

A Gloved Finger Against a Protein in the Blood

The prostate is a walnut-sized gland below the bladder that helps make the fluid in semen. A digital rectal exam, or DRE, is the physical check. A clinician uses a gloved finger to feel the back wall of the gland through the rectum, hunting for lumps or unusual firmness. The PSA blood test measures prostate-specific antigen, a protein the prostate releases into the bloodstream. Higher levels can signal cancer. They also rise for entirely harmless reasons, which is why no single number is a diagnosis.

Eight Studies, 85,798 Men, Two Plain Measures

Rather than enrolling a new group, the researchers combined eight existing studies: three randomized trials and five prospective ones, together covering 85,798 men undergoing prostate screening.¹ They calculated two things anyone can picture. The detection rate is the share of everyone screened in whom a cancer was actually found. The positive predictive value is the share of men with an abnormal result who truly had cancer. The rectal exam’s detection rate and predictive value were the review’s prespecified main measures, chosen because guidelines recommend the exam alongside PSA despite limited screening evidence.¹ Pooling this way reflects how the tests perform on average across many real-world settings.

3% Flagged by PSA, About 1% by the Exam

The exam flagged cancer in about 1% of the men screened. PSA flagged it in about 3%, roughly three times as many. Yet for both tests, only about one in five abnormal results, around 20%, turned out to be cancer. Four in five positives were false alarms. And pairing the exam with the blood test found no more cancers than the blood test used alone.

Benign Explanations, and a German Trial at Age 45

A screening result is not a diagnosis. An abnormal exam or PSA reading most often traces to something benign, usually an enlarged prostate, a very common change with age, or inflammation of the gland. Performance also varies from one setting to the next, partly because a rectal exam depends so heavily on the individual examiner. A large German trial that randomly sorted men into different screening approaches lands in the same place. Among men screened at age 45, the rectal exam turned up cancer in about 1 in 2,000 men, while PSA testing found it in about 1 in 500, and 86% of the cancers PSA picked up had felt normal to the examining finger.² Its authors concluded that the exam works poorly as a stand-alone screening test in younger men.

Key Takeaways

• Pooled across eight studies, the PSA blood test detected about three times as many prostate cancers as the digital rectal exam, and adding the exam detected no more.
• For both tests, only about one in five abnormal results was cancer; an enlarged or inflamed prostate is a common benign explanation.
• An abnormal result on either test is not a diagnosis.

References

1. Matsukawa A, Yanagisawa T, Bekku K, et al. Comparing the Performance of Digital Rectal Examination and Prostate-specific Antigen as a Screening Test for Prostate Cancer: A Systematic Review and Meta-analysis. European Urology Oncology. 2024;7(4):697–704. link
2. Krilaviciute A, Becker N, Lakes J, et al. Digital rectal examination is not a useful screening test for prostate cancer. European Urology Oncology. 2023;6(6):566–573. link.