Back in 2012, the US Preventive Services Task Force (USPSTF) took aim at the prostate-specific antigen (PSA) screening test for prostate cancer with a blanket recommendation against it for all men. This was a big deal. The Task Force is widely seen as the top expert panel on cancer screening in the United States, and most men find out they have the disease only after a PSA test comes back with a positive result.
Cut to May 2018, and the Task Force has finalized a new statement. Instead of broadly recommending against PSA testing regardless of a man’s age, race, or family history of prostate cancer, the Task Force now states that for men ages 55 to 69, the decision to be screened “should be an individual one” informed by discussing the pros and cons with a clinician. The Task Force continues to recommend against the PSA test for men 70 and older, claiming there is no evidence they’ll live longer if treated for prostate cancer. And citing inadequate data, it makes no recommendation at all for African American men (who tend to be at higher risk for prostate cancer than men of other races), men with a family history of prostate cancer, or men younger than 55.
Why has the Task Force now made this age-specific change?
Several issues are at play. Importantly, more time has passed since the largest trials of prostate cancer screening were initially launched. And with longer follow-up, the evidence in support of screening is more favorable. For instance, the European Randomized Study of Screening for Prostate Cancer (ERSPC), which was initiated in the early 1990s, recently concluded that PSA testing in the 55–69 age group could prevent 13 prostate cancer deaths (and 30 tumors from spreading) for every 10,000 men screened over 13 years. In 2012, the ERSPC’s follow-up was limited to nine years, and the estimate then was that seven prostate cancer deaths would be prevented for every 10,000 men screened.
The task force cited yet another promising trend: more men with low-risk prostate cancer are opting for active surveillance instead of treatment. Active surveillance involves routine PSA tests, digital rectal exams, and scheduled biopsies (or MRIs), and reverts to therapy only in the event that a man’s tumor begins to grow, or if genetic tests predict the cancer could become active and spread later. With active surveillance growing in popularity, the pendulum on screening is swinging closer to its benefits and away from its harms.
Potential harms of the PSA test
Still, the harms from screening are substantial, and men need to be aware of them. Here are statistics cited by the Task Force in its new statement: It’s estimated that 15% of screened men will have false-positive results (the rate is even higher for men over 70), suggesting the presence of cancer that isn’t really there. Many such men will get a biopsy and be exposed to accompanying risks that include pain, bloody semen, and infection. And there’s a good chance the biopsy will detect a slow-growing tumor that doesn’t need treatment. Autopsy studies of men who died from other causes revealed that 20% of those ages 50 to 59 — and 33% of those 70 to 79 — had microscopic, slow-growing prostate tumors that hadn’t bothered them yet and likely never would have in the future.
Meanwhile, prostate cancer treatment is life-altering. One in five men who have their prostates surgically removed will develop long-term incontinence, and two-thirds will develop long-term impotence. Among men treated with radiation, half will become impotent and one in six will develop bothersome bowel problems. Men diagnosed and treated over the age of 70 experience the highest rates of medical complications.
Experts weighing in with editorials on the Task Force’s new statement were mostly positive. But some emphasized the potential benefits of “smart” screening that targets the PSA test at specific groups. Dr. Peter Carroll, professor and chair of urology at the University of California, San Francisco, urged that men get a baseline PSA level at 45, and suggested that men with higher levels could be retested more frequently than those with lower levels. Older men in excellent health may also consider PSA testing, he wrote, since they’re at greater risk of dying from aggressive prostate cancer. And despite the limited evidence on screening high-risk populations, such as African American men and men with a family history of prostate cancer, the case for screening them with a PSA test “is strong,” he wrote.
Questions remain for men
Ultimately, the choice to have the test depends on meaningful discussions with a doctor focusing on the risks and benefits of follow-up procedures that could be undertaken if the PSA results exceed the normal range.
In the view of Dr. Marc Garnick, the Gorman Brothers Professor of Medicine at Harvard Medical School and Beth Israel Deaconess Medical Center, and editor in chief of HarvardProstateKnowledge.org, the Task Force correctly stated in 2012 that the harms of PSA testing outweigh its benefits. Too often the PSA test leads to a prostate biopsy, he says, followed by a cancer diagnosis and “almost inevitable treatment even in men who did not need to be diagnosed in the first place.” However, Garnick also emphasized that clinicians can now better predict a cancer’s likely behavior based on the molecular features of the tumor biopsy. And with that information, fewer men are being rushed toward immediate treatment.
“The identification of characteristics that would encourage a physician to advocate that the cancer be treated is an important step forward, and is the subject of intense research to help determine what that best type of treatment should be,” Garnick said.
— Charlie Schmidt