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Why You Still Need a PSA Test

Date: September 12, 2016      Publication: Health Insider      Source:  Mark A. Preston, MD, MPH, Brigham and Women’s Hospital      Print:

More and more men are opting not to get the prostate-specific antigen (PSA) test.

After all, prostate cancer usually grows so slowly that it never has a chance to affect health—and the PSA hasn’t been shown to be a good marker for the kind of aggressive prostate cancer that’s often lethal and needs treatment. The United States Preventive Services Task Force (USPSTF) advises against using the blood test as a universal screen for all men…or even all men over, say, 50.

But there is a way to use the PSA as a heads up that you are at high risk for the really dangerous kind of prostate cancer, according to new research.

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TIMING IS EVERYTHING

According to a new study, the result of even a single PSA test, done during middle age, can predict risk for aggressive, lethal prostate cancer years, even decades, later.

Using data from the Physicians’ Health Study, researchers looked at nearly 15,000 men who had had their PSA levels tested when they were age 40 to 59. They were followed for up to 30 years, and cases of prostate cancer were recorded.

Those with the highest PSAs for their age group tended to have more prostate cancer. That’s not surprising—or particularly helpful. One reason why universal testing is discouraged these days is that many cancers found from PSAs are relatively benign, grow very slowly and never turn into the lethal kind of cancer that spreads…and kills. Getting treated for these kinds of relatively harmless cancers can lead to unnecessary, serious side effects, including urinary incontinence and sexual impotence.

But the new study found something else, too…something more disturbing. Risk for potentially lethal prostate cancer, meaning that it has spread outside the prostate and, in some cases, led to death, was also strongly associated with PSA during midlife.

This is quite different from the way PSAs were typically used—to gauge risk for prostate cancer in the next year or two, without being able to identify who would get a nonlethal versus a lethal cancer. The new research means that your PSA at mid-life is a long-term indicator of your risk for lethal prostate cancer decades later.

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The biggest risk: Men whose PSAs were in the top 10% for their age group in their 40s and 50s.

PSA levels tend to rise with age so the researchers divided the men into three age groups. Here is the risk for men in the top 10% compared with men in the same age group whose PSAs were at or below the median…

  • Men 40 to 49 years old with a PSA at or above 1.68 ng/mL were 870% more likely to develop lethal prostate cancer over the next 30 years.
  • Men 50 to 54 years old with a PSA at or above 1.96 ng/mL were 1,260% more likely to develop lethal prostate cancer over the next 30 years.
  • Men 55 to 59 years old with a PSA at or above 2.88 ng/mL were 690% more likely to develop lethal prostate cancer over the next 30 years.
  • By contrast, men who had values at or below the median for their age had very low risk for lethal prostate cancer, hovering at a 30-year risk of 2%. The median levels were 0.68 ng/mL for men 40 to 49…0.88 ng/mL for men 50 to 54…and 0.96 ng/mL for men 55 to 59.

Why is a mid-life test so meaningful? One reason may be that prostate cancer usually starts developing in men during their 40s and 50s and grows very slowly, so a measurement taken then may be an early warning sign for a cancer that develops decades later. Also, a measurement taken in middle age may be more accurate than one taken in your 60s or 70s, when benign prostate changes can affect test results.

WHAT TO DO NOW

The new study doesn’t mean that it’s time to bring back the PSA for everyone. The researchers suggest that men with high baseline PSA in their 40s and 50s undergo more frequent screening than men with lower baseline PSA. If you’re older, it may be worth checking to see what your PSAs were in your 40s and 50s, and if they were high, discussing with your doctor whether you should be more frequently monitored going forward. If you’re in your 40s or 50s, discuss with your doctor getting a baseline PSA.

Unlike earlier advice, the point isn’t to get treated at the first sign of any cancer—that’s no longer the emphasis, since that leads to overtreatment and serious side effects that can be avoided—but to better identify men who should be extra-vigilant in being monitored for lethal prostate cancer. In the near future, genetic tests may be able to signal which men are likely to develop lethal prostate cancer—so they can be treated when the cancer is at its earliest stage. Until then, the decision to get a PSA test is a personal decision that you should make with your health-care provider. To get the answers to common questions about the PSA test decision, see Bottom Line’s article “Latest Thinking On The PSA Debate.

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The good news is that, even if a PSA test leads to a biopsy and a diagnosis of prostate cancer, you have a greater chance of avoiding unnecessary treatment than ever before. That’s because more doctors and patients with low-risk cancers are opting for active surveillance, in which the cancer is monitored, and treatment only initiated if the tumor shows signs of becoming aggressive. Ironically, active surveillance can lead to more PSAs and other tests—but less unnecessary surgery and radiation. To learn more, see Bottom Line’s article “Diagnosed with Prostate Cancer? 4 Big Mistakes Men Are Making.

Source: Study titled “Baseline prostate-specific antigen levels in midlife predict lethal prostate cancer,” by Mark A. Preston, MD, MPH, Brigham and Women’s Hospital, Boston, and colleagues, published in Journal of Clinical Oncology.