PSA Test's Overall Benefit Still Unclear: Study
WEDNESDAY Aug. 15, 2012 -- The latest entry in the scientific debate over the value of prostate-specific antigen (PSA) testing suggests its overall worth remains far from clear.
Using statistical modeling, Dutch researchers concluded its benefits are diminished by lost quality of life from serious side effects and the decision whether to screen should be left to men and their doctors.
In their study, the study author predicted that annual PSA tests for men aged 55 to 69 would result in nine fewer prostate cancer deaths (28 percent) for every 1,000 men screened.
But they were also able to quantify harm and survival on the same scale by calculating quality-adjusted life years.
With harms such as impotence and incontinence factored in, "the disadvantages of screening diminish the benefits [of added lifespan] by 20 percent," said study author Eveline Heijnsdijk, a researcher at the department of public health of Erasmus Medical Center in Rotterdam.
"Individuals and clinicians have to decide themselves whether the benefits outweigh the harms," Heijnsdijk said.
The quality-adjusted life year index is a measure that assesses the value of a medical intervention. PSA is a protein in cells of the prostate gland, and the higher a man's PSA the more likely it is he has cancer.
Dr. Louis Potters, chair of radiation medicine at North Shore-LIJ Health System in New Hyde Park, N.Y., agreed the findings suggest a need to consider each case individually.
"Once again, these results confound any definitive conclusion," said Potters. "This particular study further hardens the argument that you do need to think about it, you do need to personalize it and there isn't a one-size-fits-all approach, as disappointing as it might be for each side of the argument."
The study is published Aug. 16 in the New England Journal of Medicine.
In May, the U.S. Preventive Services Task Force recommended against routine PSA screening, saying too many non-dangerous cancers were being treated aggressively and resulting in unnecessary harm.
But a July study in the journal Cancer found that not screening American men would triple the number developing advanced cancer, and the American Society of Clinical Oncology recommended that men with a life expectancy of more than 10 years talk with their doctors about getting the test.
This new analysis uses information gleaned from the European Randomized Study of Screening for Prostate Cancer, which evaluated the effect of PSA screening on prostate cancer mortality in 162,000 men in seven countries.
The scientists confirmed that PSA screening would save lives, and using a quality-adjusted life year index they concluded that 73 total life-years would be gained for every 1,000 men screened. However, only 56 of the 73 life-years gained would be considered "quality" years once adjusted for adverse effects related to overdiagnosis and treatment of cancers that would never turn lethal.
Potters asserted that the argument whether or not to screen would "go away" if more patients underwent surveillance of their prostate cancer rather than active treatments such as prostate removal or radiation -- therapies the study noted leave between 42 percent and 88 percent of men impotent.
Between 40 percent and 48 percent of men diagnosed with prostate cancer are eligible for surveillance, which closely monitors their cancer, he said.
"That's the opportunity that's sort of lacking," he added. "We're getting blinded by the argument of screening when I think the argument is really over treatment."
The U.S. National Cancer Institute offers a fact sheet about PSA testing.
Posted: August 2012
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