Yearly PSA Tests: Do All Men Need Them?
Your level of PSA (prostate-specific antigen) is 1.5 -- just like it was last year, and the year before that. Your yearly rectal exam was normal. Do you need a PSA test next year?
Probably not, says urologist H. Ballentine Carter, M.D. Recently, he looked at the long-term PSA measurements of 312 men who participated in the Baltimore Longitudinal Study of Aging. (Since it was begun in 1958, some 1,500 men have participated in this study, returning every other year for physical examinations and a battery of medical tests. Their blood samples from every check-up are stored for future studies.) With this treasure trove of data, Carter says, "we could go back and look at early PSA levels in men with and without cancer, and then look to see how quickly those men reached a PSA that was abnormal" -- higher than 4.
"Our questions was, for men with really low PSA values, would it be safe to wait more than one year to repeat this test?" If so, some $126 million could be saved every two years in men between ages 50 and 70, Carter estimates.
"We looked at how quickly these men reached the PSA level of 4, depending on what their starting level was. And it turned out that if you started with a PSA level less than 2, there was no reason to repeat the PSA the following year, because no one reached a PSA of 4 in one year. It took two years, and only a very small percentage of people even did so in two years."
However -- even though men would still receive a yearly rectal examination -- would it be safe to wait an extra year for the PSA measurement? Would any cases of significant prostate cancer be missed? So Carter did a further study, on a data base of 389 Hopkins patients, conservatively defining a curable tumor as Gleason 6 or below, and being confined to the prostate.
His findings: "If you have non-palpable cancer (in other words, a tumor that can't be felt on a digital rectal examination) and a PSA less than 4, there is a 95 percent chance that you have curable cancer. There's also a 50 percent chance you may have an insignificant tumor (which may never need treatment). If you have a non-palpable tumor and your PSA is between 4 and 5, there's still a 90 percent chance that you have a curable tumor -- but only a 19 percent chance that you have insignificant cancer."
In the past, Carter says, "our approach has been, the more cancers we pick up, the better. But this approach is designed to optimize the detection of curable, and at the same time, significant cancers."