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PSA test -- yes or no? More fodder for that roiling debate

August 16, 2012|By Rosie Mestel | Los Angeles Times
  • Levels of PSA in the blood are used to screen for prostate cancer. But the test is controversial. A new study tries to figure out how many QUALITY years the test would give to men.
Levels of PSA in the blood are used to screen for prostate cancer. But the… (Mark Boster / Los Angeles…)

Should men get routine PSA tests to screen for prostate cancer? It’s controversial. In May, a government advisory panel -- the U.S. Preventive Services Task Force -- recommended against the screens for men of any age.

A new study offers more information. It tries to figure out whether the test serves men by incorporating how they would feel about the things that could happen to them once they get the test.

The task force’s reasoning back in May was this: PSA screens may catch cancers, but a lot of those cancers would never have done the man any harm. Meanwhile, intervention can harm. Biopsies can lead to infections, and treatments can render men impotent or incontinent and in some cases even kill them.

The task force concluded that the harms outweighed the benefits, based on two large studies.

One of the studies, of 76,693 U.S. men, found no difference in death rates between a group of men who had PSA tests and another group that didn’t.

The other study, of 182,160 men in Europe, also found no death rate difference overall between those who got screens and those who didn’t. It did find a benefit in a subset of men aged 55 to 69, however.

The new paper by Eveline A.M. Heijnsdijk and co-authors, published in the New England Journal of Medicine, also looked at the European study. But this time, the authors did something a bit different with the data. They modeled it to see how PSA screening affected the years of good-quality life the population of men would have in both groups -- how many quality years would be lost and how many would be gained through being screened or not being screened.

Obviously, the results will be different for each man depending on what happens to him. Does the screen detect high blood PSA levels? Did he get a biopsy? Did the biopsy go smoothly or were there side effects? Was he treated, and did he experience side effects afterward? How long did he live in this state versus that state? It will also be different depending on who he is.

The analysis had to devise numbers on what constituted quality of life. It scored an outcome of “death or worst imaginable health” as zero. It scored “full health” as 1. It scored other outcomes, such as urinary incontinence, for example, from past studies seeking to address men’s feelings about various health states.

Using the data they had from the study -- on rates or biopsies, cancers being found, side effects experienced and the numbers of years men spent in each state -- the scientists came up with an overall sum of good years gained or lost for men who got screened or didn’t.

They found that in men ages 55 to 69, there would be nine fewer prostate cancer deaths per 1,000 men screened and a total of 73 life-years gained.

But when they made their adjustments for life quality, they found that the number of good-quality years gained per 1,000 men was 56. In other words, the benefits of PSA screening still remained in that study but were decreased.

This -- how men feel about outcomes -- is a very important thing to know if one is to decide what to recommend regarding PSA screening, commented Dr. Harold C. Sox of the Dartmouth Institute for Health Policy and Clinical Practice in Hanover, N.H., in a commentary accompanying the report.

Still, Sox wasn't satisfied with the life-quality values assigned to men’s different health states -- namely, how did the authors come up with them? Research in this area is “meager,” he wrote, and the studies the authors cited didn't offer robust numbers. That was “the least satisfactory aspect of this report,” he wrote.

For now, Sox concludes that "guidelines should avoid recommending for or against PSA screening. Instead, they should recommend shared decision-making" between patient and doctor, thus ensuring that each individual's feelings about all the things that may or may not happen to him can be taken into account. 

A brave attempt, in other words, but not there yet.

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