P.S.A. Test No Longer Gives Clear Answers
By GINA KOLATA
Published: June 20, 2005
LAST November, Rabbi Samuel M. Stahl was worried that he might have prostate cancer. He had had two P.S.A. tests in the past six months. Both times, his levels were well within the range that had been considered normal, but the second level was higher than the first.
Forum: Health in the News
His internist told him to relax. The blood test looks for a protein, the prostate specific antigen, which can signal cancer. Only test results higher than 4 were worth worrying about, the doctor contended, and both tests were below that.
But Rabbi Stahl, who lives in San Antonio, remembered advice he had gotten from a stranger three years ago that suddenly felt eerily prescient.
The rabbi was walking out of the city's Ecumenical Center for Religion and Health when he passed a man who was walking in.
"The man said, 'Are you here for the prostate cancer support group?' " Rabbi Stahl recalled. "I said no. Then he said: 'I just want to give you a bit of advice. Don't pay attention to the absolute P.S.A. number, but if you see it rising, that's a cause for concern.' "
Rabbi Stahl's first P.S.A. was 2.4. But the second one was 3.4. He had to find out: was that jump ominous or inconsequential?
Rabbi Stahl had stumbled into one of the great issues in medicine today. No longer is the P.S.A. test a simple screen with a sharp cutoff at 4. Now, prostate cancer experts say, all bets are off.
The P.S.A. test "is just not as discriminating as we thought it was," said Dr. Michael J. Barry, a professor of medicine at Harvard Medical School.
As a result, many experts are suggesting that the P.S.A. not be the single focus of prostate cancer screening, but rather one piece in a puzzle with other risk factors. Some experts are also asking doctors to be more open to the idea that some men may be better off forgoing treatment and instead be monitored regularly for changes in their tumor's growth. The muddied story emerged in a sequence of medical papers over the last year.
First Dr. Ian M. Thompson Jr., chief of urology at the University of Texas Health Science Center at San Antonio, published a paper in The New England Journal of Medicine reporting that biopsies found prostate cancer in as many as 15 percent of men with P.S.A. levels below 4.
Then Dr. Thomas Stamey, professor of urology at Stanford University School of Medicine, published a paper in The Journal of Urology saying that P.S.A. tests were virtually useless. In most men, P.S.A. levels of 2 to 10 are caused by nothing more than a harmless enlargement of the prostate that occurs when men age. But prostate cancer is so common that biopsies find prostate cancer in most middle-aged and older men if doctors look hard enough. So the results would be the same if doctors simply biopsied men age 50 and older than if they did a P.S.A. test first.
And last month, Dr. Peter C. Albertsen of the University of Connecticut Health Center published a study in The Journal of the American Medical Association saying men with prostate cancers that do not look particularly aggressive under a microscope - the majority of men whose cancers are found with P.S.A. tests these days - can do perfectly well with no treatment for at least 20 years. All they need is to be monitored by a doctor to ensure that their P.S.A. levels are not shooting up.
On the other hand, a Swedish study published last month in The New England Journal of Medicine lumping men with more as well as less aggressive cancers found that those who had their prostates removed had a lower risk of death and of metastatic cancers than those who did nothing. But these men generally started out with larger tumors than the ones that are now being found with P.S.A.'s.
So what is a man to do?
The problem, said Dr. Timothy Wilt, a professor of medicine at the Minneapolis V.A. Medical Center, is that most men eventually develop prostate cancer, but most of the time it grows so slowly that it never causes problems and eventually they die of something else, never knowing they had cancer. Unless, of course, a doctor starts biopsying their prostate. With annual P.S.A. tests, sooner or later many men will end up with a biopsy.