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Early prostate cancer detected in molecular-based urine test
PHILADELPHIA (April 2, 2000) -- Researchers at Fox Chase Cancer Center in Philadelphia, Pa. say prostate cancer can be detected in urine. The findings of a new study were presented today at the American Association for Cancer Research in San Francisco.
"Prostate cancer is curable if detected early and it is likely that there are cancer cells in body fluids years before cancer is clinically detectable. If we can find those cells, we can cure more prostate cancers," explained Paul Cairns, Ph.D. of Fox Chase Cancer Center.
Cairns and his colleagues at Johns Hopkins University (JHU), chose to screen urine DNA for a common, early genetic change unique to cancer cells called hypermethylation at the glutathione-S-transferase (GSTP1) gene using a sensitive PCR (polymerase chain reaction) test.
GSTP1 hypermethylation is found in more than 90% of prostate cancers but not in normal tissues or in BPH, making it a very specific marker for the disease.
Investigators collected tumor samples and urine specimens from 28 men known to have surgically curable prostate cancers. Specimens were coded to prevent investigator bias. Of the 28 tumor DNAs, 22 showed GSTP1 methylation and could be compared with urine samples. For 6 of these 22 tumors, the corresponding urine DNA was also positive for GSTP1 methylation, confirming the potential of this test to detect curable prostate cancers. There were no false-positive results.
"We are optimistic that future research and continuing improvements in molecular technology will increase the detection rate. Screening tests should be reliable, inexpensive, and noninvasive. Urine tests meet these standards," Dr. Cairns said.
"We already know," Cairns said, pointing to work by Dr. Sidransky at Johns Hopkins, "that a urine test can detect almost all bladder cancers and many kidney cancers. In the future, it's quite possible that the same urine specimen could be used to test for prostate, bladder and kidney cancer"
According to the report, the dramatic increase in prostate cancer detection between 1986 and 1991 is usually credited to the increasing use of PSA testing. Of prostate cancers currently detected, about 75 percent are associated with an abnormal PSA.
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Fox Chase Cancer Center, one of the nation's first comprehensive cancer centers designated by the National Cancer Institute in 1974, conducts basic and clinical research; programs of prevention, detection and treatment of cancer. F or more information about Fox Chase activities, visit the center's web site at: www.fccc.edu
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