Repeating Prostate Screenings Is Urged
A commonly performed blood test for prostate cancer frequently produces false positive results and ought to be repeated at least once before an invasive biopsy is performed, researchers said Tuesday.
“We recommend having the findings confirmed by repeating the PSA [prostate specific antigen] test after waiting at least six weeks,” said study author Dr. James Eastham, a surgeon in the department of urology at Memorial Sloan-Kettering Cancer Center.
“Even if the repeat test shows an elevated level, prostate cancer will only be discovered in about one quarter of men who undergo biopsy,” in which cells are surgically extracted from the prostate, he said. “A single, elevated PSA level does not automatically warrant a prostate biopsy.”
The study, published in this week’s Journal of the American Medical Assn., looked at frozen blood samples from 972 men, with a median age of 62, to test for the antigens that may indicate cancer of the prostate.
Although one out of five of the men had an elevated PSA level at some time during the study, the level subsequently returned to normal in nearly half the men -- making a biopsy unnecessary.
“These natural variations in PSA detract from its use as a screening tool,” said Colin Begg, an epidemiologist at Memorial Sloan-Kettering. “A policy of confirming newly elevated PSA levels several weeks later may reduce the number of unnecessary procedures as well as the number of men diagnosed with a small, incidental tumor that poses no threat to life or health.”
Delaying the cancer diagnosis by a few weeks or months for men who actually have the disease should not affect the efficacy of treatment, the report said.
About 220,000 cases of prostate cancer will be diagnosed in the United States this year, the most commonly diagnosed cancer among American men. It afflicts one of every six American men in their lifetimes, and is expected to kill approximately 29,000 this year.
Increasingly, early detection of the disease, often through a PSA test, improves the chances of catching it while it is still treatable.
