Study: PSA Testing Cuts Worst Prostate Cancers
Threefold Fewer Metastatic Prostate Cancers Since Routine PSA Testing
"The reason our study has some meaning is that all a screening test can give you is a shift to lower-stage disease," he says. "It can't cure the disease and it can't prevent the disease. All it can do is allow you to catch it earlier and give appropriate treatment for the stage of disease you have caught it at."
Kramer notes that another study using National Cancer Institute data recently found that late-stage prostate cancers declined in men over age 75 after it was recommended that they stop getting PSA tests. It's highly unlikely that not getting screened prevented these cancers. But it does show how easily false results creep into look-back studies.
PSA Screening Controversy
The U.S. Preventive Services Task Force recently recommended against routine PSA screening.
"At best, PSA screening may help one man in 1,000 avoid death from prostate cancer after 10 to 14 years," task force co-chair Michael LeFevre, MD, MSPH, of the University of Missouri, writes in an email to WebMD. "We now know that the PSA test harms many more men in the course of testing and treatment after a positive result."
But what about Messing's study?
"This study is not a randomized trial, and the results don't tell us much about whether screening reduces a man's chances of having metastatic prostate cancer," LeFevre notes. "Since death from prostate cancer will nearly always be preceded by metastatic disease, one would expect a significant decline in metastatic disease to be accompanied by a significant reduction in deaths. But that is not what the clinical trials show."
Messing agrees that his study is not a screening study, although he argues that the European trial of PSA screening did indeed show the same reduction in metastatic cancer as his study predicted. And this reduction, he says, argues strongly in favor of routine PSA tests for all men starting at age 50 and older, and for higher risk men starting in their 40s.
Kramer says Messing is right when he says screening itself doesn't save lives. Only treatment can do that. And the evidence unfortunately shows that prostate cancer treatment isn't as good as everyone would like it to be.