May 1, 2000 (Atlanta) -- Researchers have discovered a new marker that may soon make prostate cancer diagnosis as quick and easy as a simple urine test.
The tool currently used for detecting prostate cancer -- PSA, or prostate specific antigen, testing -- is woefully inadequate, says lead researcher Mark Stearns, PhD. Not only does the test require a blood sample, it's not very accurate. "At least 25% of patients with cancer show up negative for PSA," he tells WebMD. And patients with benign, or noncancerous, prostate problems often test positive for PSA.
So Stearns and his team at Medical College of Pennsylvania in Philadelphia "attempted to develop a better, less-invasive [test]. We were able to identify a marker that is present in the urine of patients with cancer but not in patients with benign disorders," he says. They presented their findings here Monday at a meeting of urology experts.
First, the researchers performed tests on cancerous and noncancerous prostate tissue. They tested more than 4,000 substances and identified what seems to be a new marker that appears only in cancerous tumors. This new marker is a protein called prostate specific transcription factor (PSTF-1).
Next, they developed a simple urine test that doctors could use to screen patients for the marker. When they tested urine samples from more than 200 patients with cancer or benign prostate disease, they found that the test provided very accurate results. One hundred percent of the positives were from patients who had cancer, and nearly all of those with negative urine tests had no cancer.
Even more important, says Stearns, unlike PSA testing, the amount of PSTF-1 in the urine was a strong indicator of how severe the patient's cancer was. This means that the test could eventually be used to see whether prostate cancer treatment is working.
Things are "moving fast," says Stearns. He is in the process of setting up a large study to confirm these results. If the findings look good, drug companies should begin the process of developing the test within the next few years.
Stearns tells WebMD that he sees the test being used for routine screening, much like the annual Pap smear that women obtain to screen for cervical cancer, and for helping doctors and patients decide the best course of action.