Study gives digital prostate exams the finger as cancer screening tool

A new study has found that digital rectal examination alone or in combination with a blood test does not improve prostate cancer detection compared to the blood test alone. The findings suggest that digital exams are less effective than thought and could be omitted from prostate cancer screening in men who don’t have clinical signs and symptoms.

The go-to methods for screening and detecting prostate cancer are a digital rectal examination (DRE) and a blood test to measure prostate-specific antigen (PSA) levels. PSA is a protein produced by both cancerous and non-cancerous prostate tissue so that elevated levels can indicate either cancer or a benign enlarged prostate. DRE requires no further explanation; it’s often used in combination with PSA as a diagnostic tool.

Is one method better than the other at diagnosing prostate cancer, or are both necessary? A new study by researchers from the Comprehensive Cancer Center at the Medical University of Vienna (MedUni Vienna) and Vienna General Hospital may have answered that question.

The researchers undertook a meta-analysis of eight studies involving 85,738 participants ranging in age from 45 to 98, of which three were randomized controlled trials, and five were prospective diagnostic studies. Studies eligible for inclusion evaluated men undergoing screening for prostate cancer using DRE as a screening method compared to PSA testing to assess the diagnostic effectiveness of these methods according to the positive predictive value and cancer detection rate.

The data suggested that the combination of DRE and PSA for prostate cancer screening had no significant benefit over PSA alone in terms of predicting and detecting cancer. While the findings indicated no significant difference in predictive value between DRE and PSA, PSA had a significantly higher cancer detection rate than DRE.

“The validity of rectal examination in detecting prostate cancer is not particularly impressive, suggesting that it may not be necessary to perform this examination routinely as part of screening in the absence of clinical symptoms and signs,” said Shahrokh Shariat, corresponding author of the study.

DRE is a highly subjective test, compromising its effectiveness as a screening method. A 2008 study found that the percentage of suspicious DREs varied between examiners, ranging from 4% to 28%. Looking at studies that considered alternative screening and detection methods, particularly one that demonstrated a significantly higher cancer detection rate for MRI (63%) than for PSA (29%), the researchers suggest that MRI and PSA replace the combination of DRE and PSA.

The current study opens a discussion about the effectiveness and benefits of DRE in the early detection of prostate cancer. Considering that the relative cost of a PSA test is low and that DRE induces physical discomfort and psychological stress in patients, the data, taken together, indicate that PSA seems to be a more effective, less distressing screening test than DRE, according to the researchers. They also point to a dislike of DRE as a reason that men frequently avoid prostate cancer screening, which can put them at risk.

“The continuous improvement of prostate cancer screening methods remains of paramount importance to protect the health and well-being of men worldwide,” Shariat said. “We certainly hope that by removing this barrier, more men will go for prostate cancer screening."

The study was published in the journal European Urology Oncology.

Source: MedUni Vienna