July 26, 2017
Blood tests

New Advice (Again) About PSA Testing

by Berkeley Wellness  |  

When the influential U.S. Preven­­tive Services Task Force recommended against routine PSA screening for prostate cancer in 2012, many men were surprised, confused, or even angry. Some men and their doctors followed the advice and stopped screening or didn’t start, while others ignored it. Now the Task Force has changed its collective mind. It has revisited the subject, as it does every five years, and issued new draft guidelines that leave the decision about screening up to individual men, ages 55 to 69, depending on their “values and preferences” and in consultation with their doctors. It still recommends against screening men 70 and older. (Note: Prostate cancer screening means testing men without signs, symptoms, or history of the disease.)

The new guidelines align with those of the American Cancer Society, American Urological Association, and American Academy of Physicians, though these groups say the discussion about the pros and cons of screening should begin around age 50 or even 45 and that most men should stop at 75, which is what we have also advised. (Some groups, such as the American Academy of Family Physicians and the Canadian Task Force on Preventive Health Care, still recommend against routine screening.) In some ways, the Task Force is going back to its pre-2012 guidelines, which said there was insufficient evidence to recommend for or against PSA screening.

Why the change?

The PSA test measures blood levels of the prostate-specific antigen, a protein produced by prostate cells. PSA testing has long been a contentious issue be­­cause, though it is likely to benefit some men, it’s not clear how many lives it actually saves. Meanwhile, the risks are well known, including overdiagnosis, overtreatment, and the serious adverse effects that treatment may en­­tail. Thus, ex­­perts have had difficulty in advising men about what to do.

The Task Force is changing course largely because it now sees the benefit/risk ratio somewhat more favorably. It says that while research is still inconsistent, longer-term follow-up data from a key European study strengthen the case that screening slightly reduces the risk of dying from prostate cancer. It cites estimates that for every 1,000 screened men (ages 55 to 69) over a 10-to-15-year period, 240 will get a positive PSA result, leading to 100 positive biopsy results and ultimately one or two fewer deaths from prostate cancer.

In addition, the Task Force notes there are now better ways to reduce the potential harms. For instance, improvements in how PSA results are interpreted and utilized allow doctors to better predict which cancers will behave aggressively and spread and which don’t need to be treated. What’s more, treatment options are now better and more clearly understood. Notably, re­­cent studies have confirmed that active surveillance (also called watchful waiting) can safely allow most men diagnosed with less-aggressive prostate cancer to monitor it for years without rushing into treatment—and more men are now opting for that, reducing the potential harms of un­­necessary treatment.

PSA ups and downs

PSA is not a cancer test per se. Blood levels can rise as a result of a variety of prostate disorders—such as infection, benign enlargement, or cancer—or sometimes for no apparent reason. The test, which is easy to do and inexpensive, was introduced in the 1980s to monitor men already diagnosed with prostate cancer. But doctors soon began using it to screen millions of healthy men.

Even though the PSA test can detect cancer early, that isn’t always a good thing. Age greatly increases the risk of prostate cancer—about 90 percent of cases are diagnosed in men over age 55, and 70 percent of deaths occur after age 75. However, the great majority of prostate tumors, especially in older men, remain small, develop very slowly or not at all, do not spread, and cause no symptoms. Far more men die with prostate cancer than from it. In fact, autopsy studies reveal that more than one-third of men in their fifties and three-quarters of those over 75 had prostate cancer—usually small and harmless—and the vast majority never knew they had it and died from something else.

Unfortunately, PSA is not a very good screening test because it produces lots of false alarms and misses many cancers (since some men with prostate cancer have normal PSA levels). The only way to de­­termine which men with elevated PSA have cancer is with a biopsy. Fewer than half of them turn out to have cancer. (Newer imaging techniques may improve the accuracy of biopsies.)

Among men who are diagnosed with prostate cancer, the Task Force estimates that up to half have cancer that would never affect their health; this is called overdiagnosis. But abnormal biopsy re­­sults often lead to the treatment of these small, slow-growing cancers. And standard treatments such as radiation and surgery to remove the prostate often produce impotence, urinary incontinence, and other complications.

The good news is that death rates from prostate cancer have been declining since 1990, and some of this improvement can be attributed to PSA screening, though better treatments probably deserve much of the credit. But even data showing that screening saves lives present a sobering picture. It’s estimated that for every man whose life is prolonged because of PSA screening, somewhere between 30 and 100 men end up being treated for a cancer that was never going to harm them. Most men treated with radiation or surgery will have potentially serious complications, according to the Task Force. Such numbers are im­­proving, however, thanks to more men opting for active surveillance.

And, of course, some men with fast-growing prostate cancer will die from it even if PSA screening detects it early and they are treated for it.

A PSA Talk With Your Doctor

When it comes to PSA screening for prostate cancer, experts recommend that men have a balanced discussion with their doctors about its pros and cons. A new study finds that most do not.

Our advice

We agree with the Task Force’s new draft recommendation that PSA screening should be a personal decision and that men should discuss the pros and cons with their doctors. But like the American Cancer Society, we think this should start at about age 50 (not 55, as the Task Force advises), and even earlier for men who are at higher risk (see inset below). Keep in mind, for men who decide to be screened, no one knows what screening intervals are optimal; some studies suggest once every two to four years if PSA level is low. Even if they get screened, we think that men can stop at age 75 (not 70), since further testing is un­­likely to prolong lives. But this too is a personal decision, based on a man’s preferences and overall health.

Ultimately, it’s up to you how you want to play the odds, but it should be an in­­formed decision. You may decide to be screened, for example, if you place greater value on finding cancer early, despite the uncertain benefits and known risks. In contrast, you may decide against it if you fear that getting abnormal PSA results will land you on the “slippery slope” of overdiagnosis and overtreatment.

Several organizations and medical groups offer decision aids to help men de­­cide about PSA screening. These include the American Society of Clinical Oncology and the American Cancer Society.

Who's at Higher Risk for Prostate Cancer?

Besides increasing age, several factors boost a man's risk of prostate cancer: family history, race, and genes.

Also see Is Metastatic Prostate Cancer 'Skyrocketing'? and Cancer Screening: It's Your Decision.