|PROSTATE TESTS OVERDIAGNOSE CANCER|
March 10, 2009 Journal of the National Cancer Institute
For years there's been good research out there to tell us that we find prostate cancer where there isn't. This has been especially true when comparing the US versus European countries like Sweden. Coming from the National Cancer Institute as this is, perhaps American doctors will start paying attention.
According to this new study, as many as two of every five men whose prostate cancer was caught through a PSA screening test have tumors too slow-growing to ever be a threat. The work "reinforces the message that we are overdiagnosing prostate cancer," said Dr. Len Lichtenfeld of the American Cancer Society, who was not involved in the new study.
More than 186,000 U.S. men will be diagnosed with prostate cancer this year, and nearly 29,000 will die, according to cancer society estimates. Many men have had a blood test that measures prostate specific antigen, or PSA. This is what's creating the problem. Most men who undergo a biopsy for an abnormal PSA test don't turn out to have prostate cancer; high PSAs often signal a benign enlarged prostate. Of those who do have cancer, there's no proof yet that early detection saves lives - as most prostate tumors grow so slowly that had they not been screened, those men would have died of something else without the anxiety.
This new study, which tracked prostate cancer diagnosed in U.S. men ages 54 to 80 between 1985 and 2000, and used three different models developed by cancer centers to more accurately estimate overdiagnosis. Depending on how it's calculated, anywhere from 23% to 42% of PSA-detected cancers would otherwise never have been detected in the man's lifetime, concluded the team led by researchers at Erasmus University Medical Center in the Netherlands.
Why is overdiagnosis such a problem? Because finding an early tumor creates fear and forces men to choose among treatments - "watchful waiting," surgery, hormone therapy, radiation. All treatments can cause symptoms like incontinence and impotence. So men whose tumors wouldn't have been a threat suffer serious side effects for no gain. Enough men have complained about serious quality of life issues that national health guidelines issued last year said men over age 75 shouldn't undergo PSA screening, while younger men should make an individual choice after hearing the pros and cons and weighing their own cancer risk.
The new study's estimate of U.S. overdiagnosis probably is too low. Ever since 2000, doctors have begun performing biopsies for lower PSA levels than once were the trigger. When the treatment cause such health issues, does the diagnosis make the patient's life any better?
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