Prostate cancer is the third most common cause of cancer deaths in men in Kentucky and throughout the United States.
The current method of screening for prostate cancer uses a blood test that measures levels of a protein called prostate specific antigen, or PSA. Since the PSA test was introduced in 1986, an additional 1 million men have been diagnosed with and treated for prostate cancer.
However, several recent studies have raised questions about the value of the specific screening test in actually preventing prostate cancer deaths.
The controversy over the PSA test arises from the fact that we're now finding cancers in earlier stages, some of which are non-lethal. These are low-volume, low-grade cancers that may not cause any problems. The dilemma is, however, that we can't tell you which of those cancers will cause a problem and which ones won’t.
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There have been studies that confirm that “watchful waiting” or “active observation” for appropriate low risk cancers is safe, but approximately 20-30 percent of men will eventually go on to treatment. So for some men, watchful waiting should be added to the discussion list if they are diagnosed with prostate cancer. We need to continue to do research and find ways to accurately characterize the risk of progression for each individual cancer.
PSA is a normal protein made in the prostate gland. A number of conditions can cause it to be elevated; cancer is just one of them. An enlarged prostate, infection, or trauma to the prostate can result in higher PSA levels.
Over the years, we've used the PSA test differently. At first we relied on absolute numbers for the level of PSA, but it's hard to fit one number to everyone. More recently, we've used the PSA as an individual test, for a baseline, as in mammogram screenings. With follow-up screenings, we watch what happens to the level. If it's a flat curve, we know the individual's risk for cancer is lower. If it's a steeper curve, there is more cause for concern.
I think it's good for a man to get a baseline PSA screening beginning at age 40 if there's a family history of prostate cancer and at age 45 if not. Younger men have fewer confounding factors such as an enlarged prostate. After that, if everything is normal, they should have annual screenings. If, after 10 years, there is no increase in PSA levels, the patient can stretch out the testing intervals to two or three years. In men 73 or older who have other health issues, we should back away from routine screening.
It's true that some cancers are overtreated, but that doesn't mean we should stop PSA screening. We do need to exercise better judgment in treating prostate cancer. That's starting to happen. Our focus and our efforts should be on sorting out which prostate cancers need to be treated and which can be safely observed.
Dr. Stephen E. Strup is the James F. Glenn Professor and chief of urology in the University of Kentucky College of Medicine.