A new blood test for prostate cancer could eliminate 120,000 biopsies a year in the United States, researchers say.
"By eliminating these biopsies, you're not only going to save money, but you're going to spare men the anxiety of a false alarm and the discomfort of going through an unnecessary procedure," said Dr. William J. Catalona, director of urologic surgery at Washington University School of Medicine in St. Louis. He is lead author of a study published in Tuesday's Journal of the American Medical Association.The new test, approved by the government in March, measures blood levels of "free" prostate-specific antigen, a protein produced by the prostate gland. The traditional PSA test, used since the early 1990s, measures the protein in a different form, when it is bound chemically to another substance.
The new test does not replace traditional PSA testing; it is given as a follow-up when the traditional PSA test yields uncertain results.
Previously, the only way to resolve the uncertainty was to do a biopsy, even though only 25 percent of men in the uncertain range have prostate cancer.
The study found that when 25 percent or less of circulating PSA was chemically free, cancer was present 95 percent of the time. The lower the percentage of free PSA, the more aggressive the cancer.
Free-PSA testing could eliminate the need for about one-fifth of all prostate biopsies performed in the United States each year, Catalona said.
At about $1,200 for a biopsy vs. $65 for a free-PSA test, the new procedure could save $136 million a year.
Prostate cancer is the most commonly diagnosed cancer among U.S. men and the second deadliest, behind lung cancer.
This year, 184,500 U.S. men will be diagnosed with prostate cancer and more than 39,200 men will die from it, the American Cancer Society estimates.
Traditional PSA testing alone could reduce deaths from prostate cancer by more than two-thirds if used routinely, recent research indicates. However, one troubling aspect of traditional PSA testing has been the needless biopsies it has led to.
A spokesman for the American Urological Association said the new test will be a useful addition to prostate-cancer detection.
However, "there are other factors that might increase risk of cancer being present" and might necessitate a biopsy, said the spokesman, Dr. Mark S. Austenfeld, a urologist in Kansas City, Mo.
For example, blacks run a higher risk of prostate cancer, as do men whose traditional PSA levels are rising and men with previous biopsy results showing precancerous signs.