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Experts say a combination of screening tools is probably best for detecting prostate cancer. ljubaphoto/Getty Images
  • Researchers say a digital rectal exam alone is not an accurate way to detect prostate cancer.
  • They recommend combining the exam with another screening tool, such as a prostate-specific antigen (PSA) blood test.
  • Experts note that digital rectal exams are inexpensive and can be done during a visit to the doctor’s office, but they acknowledge that many men prefer not to have the intrusive exam.

German scientists say digital rectal exams may not be accurate enough to be a reliable screening tool by itself for prostate cancer.

The digital rectal exam (DRE) is still widely used by medical professionals to check the prostate gland for unusual lumps or swelling or lumps in the rectum that can indicate prostate cancer in men.

For example, in Germany, it’s still the sole method used in national screening programs to detect the disease.

New research by scientists of the PROBASE trial, coordinated at the German Cancer Research Center in Heidelberg, says the technique may miss many cancers in their early stages.

The findings, which haven’t been published yet in a peer-reviewed journal, were presented today at the European Association of Urology Annual Congress in Italy.

Researchers say the findings could have wide implications for the concept of early detection of prostate cancer. They are calling for other testing methods to be used in routine screening.

“One of the main reasons for screening for prostate cancer is to detect it in patients as early as possible as this can lead to better outcomes from treatment,” said Dr. Agne Krilaviciute, the study’s lead author and a researcher at the German Cancer Research Center, in a press release. “But our study suggests that the DRE is simply not sensitive enough to detect those early-stage cancers.”

The PROBASE trial is a German prostate cancer screening study at four university sites (TU Munich, Hannover, Heidelberg, Düsseldorf) and involves 46,495 men 45 years old who were enrolled between 2014 and 2019.

The men have since had follow-up health assessments in the ensuing years after the screening. Half of the participants were offered prostate-specific antigen (PSA) blood tests while the others were initially offered DRE with delayed PSA screening at age 50.

Only 57 of the 6,537 men in the delayed screening group underwent DRE and were referred for a follow-up biopsy due to suspicious findings. Only three had cancer.

Krilaviciute said when compared to the detection rate using other methods, such as a PSA test, the rate of detection using DRE was substantially lower.

“The DRE was giving a negative result in 99 percent of cases and even those that were deemed to be suspicious had a low detection rate,” Krilaviciute said. “Results we’ve seen from the PROBASE trial show that PSA testing at the age of 45 detected four times more prostate cancers.”

The researchers say one of the reasons why the DRE might fail to detect cancers, particularly in younger men, is because tissue changes in the prostate could be too slight to detect with a finger.

In addition, some cancers occur in parts of the prostate that can’t be easily reached by a finger.

“Early-stage cancer may not have the size and stiffness to be palpable,” said Dr. Peter Albers, a urologist at Düsseldorf University and a senior author of the study, in a press release.

“Separate analysis that used MRI scans before biopsies to locate cancers in the prostate showed that about 80 percent of these are in an area that should be easy to reach with a finger and still cancers were not detectable by DRE,” he said.

Dr. S. Adam Ramin, a urologist and medical director of Urology Cancer Specialists in Los Angeles, told Healthline the study confirms that “DRE is as unreliable and as reliable as thought before.”

“This study only confirms that DRE alone is not a reliable screening tool,” Ramin said. “It must be combined with a PSA testing. There is a lot of controversy over the efficacy of the PSA test. Since many men do not die of prostate cancer, even if found slightly later in its natural disease process, some argue that PSA testing does not save many lives. Some estimates indicate that thousands of PSA tests have to be done to save one life.”

Ramin said PSA testing can find five times as many cases of prostate cancer earlier than a DRE, which doesn’t necessarily mean it saves five times as many lives.

“Most prostate cancers grow slowly and do not result in the death of patients,” Ramin told Healthline. “Therefore, while PSA will find cancers earlier than DRE, PSA testing does not necessarily save significantly more lives than DRE as a standalone test.”

Dr. Michael Leapman, an associate professor of Urology at Yale School of Medicine and Clinical Program Leader for the Prostate and Urologic Cancers Program at Yale Cancer Center in Connecticut, told Healthline that getting men to undergo the digital rectal exam has always been a challenge.

“For many patients, it is a barrier to being screened for prostate cancer and it has risks of both false positives and false negatives,” Leapman said. “The exam does have value because it can help identify cancer in some patients where the PSA test fails to detect cancer and it is an important part of our current staging of prostate cancer.”

Leapman said an advantage of the DRE is it’s inexpensive and can be performed in an office visit.

“The limitations of DRE aren’t new,” Leapman said. “But until recently we haven’t had many good alternatives. Now, there are several additional tests that can help us identify prostate cancer and more accurately stage the disease.”

Dr. Bamidele A. Adesunloye, a medical oncologist at Genitourinary Cancer Center at City of Hope Atlanta, told Healthline that DREs should no longer be used as standalone tests.

“Old habits die hard sometimes,” Adesunloye said. “The pairing of both tests is key. Currently, we do not have sufficient evidence to support using DRE as a standalone prostate cancer screening option.”

Dr. Shawn Beck, a urologist with Providence St. Joseph Hospital in California, told Healthline it’s possible a patient’s age should factor more into testing guidelines.

“Our current screening guidelines give a large age block (50-70 or 75) to apply screening guidelines to DRE and PSA. There are no subset recommendations by age,” Beck said. “This study is suggesting that it might be more applicable to skip the DRE in younger men as it is not beneficial and may be detrimental to getting guys to come into the office.”

Which doesn’t mean the DRE test is useless, Beck told Healthline.

“The two tests were always sort of a ‘package deal’ for most of my training and current practice,” Beck said. “Urologists have many patients they have identified with having prostate cancer based just upon the DRE nodule. We also have patients that have elevated PSA that also have a DRE nodule and are ultimately found to have prostate cancer.”

Beck added it’s worth “the pain and suffering” of having both tests.

“If we can find all of them with the addition of a DRE, why not just do it? I certainly give patients a choice in my practice,” Beck said.

“They also don’t want to admit that they are getting older and certainly don’t want to see a doctor to tell them so,” Beck noted. “[They think] ’we are 45, we are still invincible.’”