September 13th, 2010
12:02 AM ET
Men with low PSA levels from a baseline blood test were less likely to develop prostate cancer compared to men whose baseline PSA levels were high, according to a new study.
The simple test may be a strong predictor of who will benefit from future screening and treatment for prostate cancer, according to the study published Monday in the journal Cancer.
More than 85,000 men, ages 55 to 74, with no previous prostate cancer history were the subjects of the study. The authors found that in order to save one life, they needed to investigate almost 25,000 men with low PSA levels but only 133 men with high ones. Similarly, they needed to treat 724 men who had low PSA levels to save one life but only 60 men whose levels were higher.
PSA, or prostate-specific antigen, is a protein found in prostate cancer tissue. When that tissue breaks down, the protein seeps into the bloodstream. The heavier the presence of PSA in the blood, the more likely prostate cancer will be dangerous and require some type of treatment, said Dr. Otis Brawley, Chief Medical Officer at American Cancer Society and a contributor to CNNHealth.com.
But aren't all cancers bad, even if a man's PSA level is low?
"There are a large number of prostate cancers that don't need to be treated because they're not a health threat to the man who has them," explained Brawley. That makes guidelines for screenings more difficult to set.
The American Cancer Society encourages men to work with their doctors to learn about the test's benefits and risks before making an informed personal decision around age 50. Research has not yet proven that the potential benefits of testing outweigh the harms of testing and treatment, explains the organization.
The American Urology Association recommends baseline screening for men at age 40 with future screenings determined in conjunction with the patient's doctor.
"This can't be done in a vacuum," said Dr. J. Brantley Thrasher, spokesman for the American Urology Association and the William L. Balk Chair of the Department of Urology at the University of Kansas. "We need to let [patients] know this is an imperfect marker, but we're getting data that may help us in the future."
It's difficult to accept the idea that you could have prostate cancer that doesn't need to be treated and could be left alone with no harm, while other men have aggressive and deadly prostate cancers. Brawley, who chooses not to be screened, thinks this is why most men get PSA tests regularly, despite the many risks associated treatment.
"By choosing to get screened, there is a guaranteed increase in diagnosis... but there is only a potential decrease in death," said Brawley.
Some of the risks of treatment include impotence, incontinence and bowel injury.
Still, Thrasher says the importance of the PSA blood test should not be diminished. He tells his patients to get regular screenings every other year or every three years after their initial test.
"I believe knowledge is power to some extent," said Thrasher. "It's risks versus benefits... and each decision point is a fork in the road where [me and patients] have to have a discussion."
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