New findings from a large study confirm that prostate cancer screening can lower a man’s risk of dying from the disease over many years—but the long-standing debate over how to best deploy screening remains unsettled.

Published in the New England Journal of Medicine, the study followed over 160,000 European men who were part of a clinical trial testing the effectiveness of prostate cancer screening. Beginning in 1993, trial participants were randomly assigned either to PSA (prostate-specific antigen) blood test screening at intervals that varied by country (see below) or to a control group that was not offered screening.

Earlier reports on the trial had shown that screening reduced participants’ risk of dying from prostate cancer, versus no screening. This latest update shows that the benefit persists, and actually grows a bit, over the long term. Over 23 years, the study found, men in the screening group were 13 percent less likely to die of prostate cancer, on average.

Mixed recommendations

While the study confirms that PSA testing prevents some men from dying of prostate cancer, it’s unclear whether or how the findings might influence current screening recommendations.

In fact, shortly after the study’s publication, an expert advisory panel to the UK’s National Health Service recommended against routine prostate cancer screening with the PSA test. It concluded that there was still not enough evidence that the benefits of routine screening outweigh the risks.

Meanwhile, in the United States, medical groups differ in their advice, but none recommend routine prostate cancer screening for all men starting at a set age. The U.S. Preventive Services Task Force (USPSTF) recommends that men between the ages of 55 and 69 discuss the pros and cons of screening with their doctor and then decide for themselves. Men ages 70 and older, however, are advised against PSA screening due to evidence that it may do them more harm than good (more on that below).

Other groups, like the American Cancer Society (ACS), advise men to begin that screening discussion sooner—at age 50 or even earlier, particularly if they are at increased risk of prostate cancer due to family history or race (Black men are at heightened risk). The ACS and other groups also eschew a strict stopping age for screening, and instead say that the decision should be based on a man’s overall health and life expectancy, as well as whether previous PSA tests were normal or abnormal.

The USPSTF recommendations are currently being updated, and it remains to be seen whether any changes will be made, as the status of this independent panel is up in the air now.

The heart of the debate

While routine screening is recommended for certain other common cancers—breast, cervical, and colorectal—prostate cancer is different. The central issue is that prostate cancer is often a slow-growing malignancy that may never progress to the point of threatening a man’s life. So routinely screening all men of a certain age may frequently detect early prostate cancers that were never destined to be fatal. That can lead to overtreatment—meaning men undergo surgeries or radiation treatments that are unlikely to benefit them but can cause significant side effects like urinary incontinence and erectile dysfunction.

Men older than 70 are at greater risk of overtreatment than younger men are; they’re also at heightened risk of getting a false-positive result on PSA testing, which may lead to unnecessary biopsies. That’s why the USPSTF advises men in that age group against screening.

However, as the NEJM study shows, screening can also prevent men from dying of prostate cancer—a substantial pro to weigh against the cons of screening. In addition, treatment guidelines have changed in recent years, in an effort to minimize overtreatment. They now emphasize active surveillance rather than immediate treatment as an option for many men, including those with low-risk prostate tumors (ones unlikely to grow quickly and spread) and older men with other serious health conditions that limit their life expectancy.

Ongoing questions

The study reported in NEJM—known as the European Randomized Trial on Screening for Prostate Cancer—is one of the largest to tackle the question of whether PSA screening actually reduces the risk of dying from prostate cancer. The simple answer is “yes, it does.”

But, as some experts pointed out upon the study’s release, PSA screening made no difference in trial participants’ overall longevity. The average death rates, from any cause, during the study period were the same in the screening and no-screening groups.

The trial was also a mixed bag in terms of how many PSA screenings participants had, and how often: Men were offered a minimum of two screenings and no more than eight, and the screening intervals varied by country—ranging from every two years to every seven years. The benefits, and risks, of screening could be different for men who have PSA tests more often or for a longer period.

An editorial published with the study highlights the most important issue: The trial doesn’t clarify how to best target PSA screening to the men who stand to benefit the most. “Whether PSA screening does more good than harm depends on how it is performed,” wrote Andrew Vickers, PhD, of Memorial Sloan Kettering Cancer Center, in New York City. “Of concern, current PSA screening policies that encourage men to make their own decisions about PSA testing exacerbate harms and reduce benefits. Rates of PSA testing are low among young men in their 50s and high among men over 70 years of age, the group most likely to be overdiagnosed and least likely to benefit from screening.” 

The takeaway: Prostate cancer screening is a complicated (and often confusing) issue. And at least for now, the questions around it—whether to screen, how often to do it, and when to stop screening—are something men need to discuss with their doctor.