Prostate-specific antigen (PSA) blood tests are likely to reduce the risk of death from prostate cancer, a new review published Thursday by an influential international scientific research organization has found. This is a change in medical evidence that could facilitate more widespread use.
The Cochrane review’s lead author, Juan Franco from the Heinrich-Heine University of Düsseldorf in Germany, said at a press conference that there was “moderate certainty” that screening tests that identify high levels of PSA as a potential marker for prostate cancer would lead to fewer disease-specific deaths. The benefits are small. The review analyzed the results of six trials involving 800,000 participants in Europe and North America and found that for every 1,000 men screened, there were approximately two fewer deaths from prostate cancer.
The authors were careful to say that their findings do not fully support PSA screening and that men should consult their doctors about the suitability of the test. Still, the finding that PSA screening reliably reduces deaths is a significant change from the previous Cochrane review published in 2013. This review did not find a similar benefit, contributing to the decline in popularity of PSA screening.
It was widely adopted as a screening tool in the 1990s, and after nearly 20 years of use, major medical organizations stopped recommending its use, and the U.S. Preventive Services Task Force (USPSTF) changed its guidelines to discourage its use, first in 2008 for men 75 and older, and then for all men in 2012.
Although studies at the time could not prove that screening saved lives, they did identify its harms. Widespread use of PSA testing has led to overdiagnosis and overtreatment, and men with low-grade, slow-growing cancers who otherwise would have lived longer and died of unrelated causes now find themselves facing the physical and emotional burden of cancer diagnosis and treatment.
Prostate biopsies carry a high risk of infection, surgery to remove tumors can cause erectile dysfunction, and radiation therapy and other aggressive treatments come with life-changing side effects. Given that half of all prostate cancers diagnosed in the United States do not require active treatment, but rather require monitoring, the risk of a patient’s health worsening during treatment is high.
Compared to the 2013 edition, the new review includes more long-term data, particularly from the ERSPC (European Study of Prostate Cancer Screening) studies, which had up to 23 years of follow-up. It was confirmed that PSA screening needs to be approached wisely but has its place. “This study is timely as it provides ample evidence that screening is beneficial and may actually save lives if provided appropriately to those most likely to benefit,” said Simpa Salami, professor of urology at the University of Michigan.
PSA screening needs to be done judiciously, but it is also unlikely to lead to a series of interventions, he said. “Currently, the selection of patients for biopsy is improving,” Salami said. “Before, we would do a biopsy on anyone just because they had an elevated PSA, but now we have other tools to further narrow down who should get a biopsy. We have biomarkers in the urine, we have biomarkers in the blood, and we have MRI images that facilitate the biopsy. As a result, we are actually maximizing the detection of high-grade prostate cancers and minimizing the detection of low-grade prostate cancers,” he said.
The review itself does not include any guidelines or treatment recommendations and will not result in any immediate changes to how screening is performed. Otis Brawley, professor of oncology and epidemiology at the Johns Hopkins University Sidney Kimmel Comprehensive Cancer Center, said that while the results are understood, it is important to put them in the context in which they were collected, and to understand what it means for the PSA test to reduce disease-specific mortality.
“A lot of people in the United States think that means, ‘Oh, if I take the PSA test, I’m doing something to save lives,'” he said. But the participants in the studies who saw the benefits didn’t just take their level of testing once, they got tested regularly and took the time to work with their doctors to interpret the results and decide on further action.
“This is different from what’s commonly done in the United States, where you pull out a PSA on a van parked at the state fair or a van parked in a church parking lot or at a football party saying, ‘Come on, come watch the game, pull your PSA,'” Brawley said. Consistent care and accurate follow-up and treatment are challenges for the U.S. health care system, he said, without which PSA testing alone will not be effective.
“I think the right thing to do in the doctor-patient relationship is that doctors should offer testing to their patients,” Brawley added, stressing that while there is evidence of benefit, the risks of overdiagnosis and overtreatment are clear. Physicians who have an ongoing relationship with their patients and can monitor PSA results over time are in a better position to reduce the risk of overtreatment because they have more data points to determine, for example, which patients need a biopsy and which do not, he said.
Brawley stressed the need to be clear about the magnitude of the benefits of testing and its ability to prevent deaths. “If 15 men die from prostate cancer, if we screened them over a 20-year high-quality screening program, we could prevent 1 in 15 deaths,” he said. “In the United States, every man who dies from prostate cancer is attributed to either the man not being tested or the doctor failing to interpret the test,” he said. “People don’t understand that the vast majority of people who would die from prostate cancer will die from prostate cancer whether they get tested or not.”
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