Healthy Living

The Most Common Prostate Cancer Screening Method Is Obsolete

Rectal exams aren't that good at finding prostate cancer.
09/12/2016 01:13pm ET
KTM_2016 via Getty Images

Prostate cancer, the second-most common cancer among American men, will kill an estimated 26,000 American men this year, according to the American Cancer Society. But the truth is, most men don’t need to undergo an annual exam for it, and they especially don’t need to subject themselves to the oldest and most commonly used way to screen for it: the digital rectal exam.

For one, it’s less than pleasant: A doctor inserts one gloved, lubricated finger into a man’s rectum to feel for any bumps or hard areas on the prostate gland to determine if the patient should have further testing for prostate cancer.

In addition to being unpleasant, the exam may also put up barriers between men and regular medical care. About one in five men say that uncomfortable body exams like this rectal screening keep them from making an annual appointment with a doctor.

Now, a new study claims that it isn’t as effective as the newer PSA test, which measures the amount of a prostate-specific antigen in the blood. If PSA levels are elevated, it could indicate that a man has prostate cancer.

Dr. Ryan Terlecki, a urologist from Wake Forest Baptist Medical Center in North Carolina, led a team that reviewed past research and data from a prostate cancer screening trial of about 38,000 men who received both the PSA test and the DRE annually for three years. They found that the rectal exam did not improve outcomes for most men compared to the PSA test.

After following these men for up to 13 years, the research team found that of the approximately 5,000 men with negative PSA results and positive DRE results ― in other words, among the men with prostate cancers that only the rectal exam could detect ― only 2 percent had cancers that needed to be monitored or treated. This small number of positive, clinically significant results the DRE detected does not justify exposing most of the men to the test, Terlecki concluded.

“When PSA testing is used, the DRE rarely assists in diagnosing significant disease,” he said. “In cases where PSA testing is used, the DRE should be abandoned in common clinical practice.”

But there’s a reason to be wary of PSA tests, too

It’s important to note that PSA is also produced naturally by the prostate, which means high readings could simply be because the prostate is enlarged or inflamed for reasons that have nothing to do with cancer, such as infection or aging.

False positive PSA tests at best worry men, and at worst result in unnecessary surgery or other cancer treatment for a tumor that wouldn’t otherwise be deadly. While exact numbers are difficult to come by, data from large trials estimate that prostate cancer screening results in overdiagnosis rates of 17 to 50 percent, according to the U.S. Preventive Services Task Force.

Because of the high risk of false positives, the task force recommended in 2012 to stop routine PSA testing among men in all age groups.

Without a perfect test, what should most men do?

It depends.

When it comes to prostate cancer screenings, medical organizations in North America and Europe are about evenly split; half agree with the USPSTF and recommend that men get no routine screening at all, while others, like the American Cancer Society, emphasize that men should make the screening decision with their doctors, keeping in mind both the harms and benefits linked to testing.

Dr. Otis Brawley, chief medical officer of the ACS, agrees with Terlecki that there are solid scientific reasons that a man can opt to skip the DRE for prostate cancer screening. But more broadly, Brawley also emphasized that men should carefully consider their need for prostate cancer screening in general, no matter what the test. As confusing as this concept may be, there are some cancers that grow so slowly that a person would die of other causes before the cancer became a serious medical problem.

”All of the studies actually indicate that we diagnose a substantial number of men who have prostate cancer, but they have a cancer that does not need to be treated or cured,” he explained.

The truth is, most men diagnosed with prostate cancer will not die from it. For all stages of the cancer, there is an almost 100 percent five-year survival rate, a 98 percent ten-year survival rate, and a 95 percent 15-year survival rate. To get a picture of how positive those stats are, the five-year survival rate for lung cancer, the leading cause of cancer death in men, is only about 18 percent.

While some men will die of prostate cancer, there are documented risks and harms that show widespread, regular prostate cancer screening may not be the best policy for most men. An estimated five in 1,000 will die of prostate cancer without screening, and four in 1,000 die with screening.

This means that screening will, at most, save the life of one man in 1,000, while causing false positives in up to 120 men per 1000. About 110 men in 1,000 will go on to be diagnosed with prostate cancer, and of these, about 90 percent will choose treatment that could cause serious cardiovascular events, deep venous thrombosis, urinary incontinence, erectile dysfunction and death. These risks are all the more untenable considering most of these men likely had a cancer that was not going to kill them.

“There’s definitely a small benefit of screening with PSAs but there’s also known harms,” explained Dr. Kirsten Bibbins-Domingo, chair of the Preventive Services Task Force and a professor of medicine at the University of California, San Francisco. “If we had a better test that identified cancers that were going to kill you, people would accept these harms.”

Another way to lessen harms would be if more doctors and patients agreed to “active surveillance” of the growth after diagnosis, which means not rushing to treatment, and instead waiting to see if symptoms emerge that signify that the cancer will be more of a problem than normal. But until that day comes, the USPSTF will not recommend routine screening for all men for prostate cancer.

However, men aren’t completely off the hook when it comes to the rectal exam; Brawley pointed out that the test is also usually administered with a colonoscopy, which is a test taken every ten years to screen for colon cancer.

“Men need to realize the potential risks and the potential benefits and then make a decision based on their values,” Brawley concluded.

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