CHICAGO -- An experimental urine test that checks for an enzyme that boosts the growth of tumors is an effective way to detect bladder cancer in early, curable stages, researchers have found.
Similar tests that check for different substances are on the market, but the new test is more accurate, said Daniele Calistri, the study's senior author and a researcher at Morgagni-Pierantoni Hospital in Forli, Italy.
''Another important advantage of this test is its ability to identify low-grade tumors," the researchers said in a report published today in the Journal of the American Medical Association.
Early diagnosis is a challenge in bladder cancer. Blood in the urine is a symptom, but it also can signal less serious conditions, and patients frequently dismiss it until the disease has progressed, said Dr. Edward Messing of the University of Rochester Medical Center.
''It's potentially a very useful test," Messing said. The study gave ''the best results I've ever seen," he added. Messing was not involved in the research.
The study involved 134 male bladder cancer patients and 84 healthy men. The test correctly identified cancer in 90 percent of the patients and ruled it out in healthy men almost as often.
Bladder cancer occurs in men much more often than women; whites, smokers, and people aged 65 and older also are disproportionately affected. More than 60,000 new cases are diagnosed each year in the United States alone. About 20 percent of patients die each year but survival chances are good with early detection, the researchers said.
The new test detects urine levels of telomerase, or what is sometimes called the ''immortalizing enzyme" because it enables cancer cells to keep growing indefinitely. Telomerase is present in almost all human cancer cells.
It is, however, rarely found in noncancerous cells. Research is investigating ways to use it as a target for both diagnosing and treating cancer, said Jerry Shay, a cancer researcher at the University of Texas Southwestern Medical Center in Dallas.
Telomerase appears late in some cancers, but early in bladder cancer, he said.
The researchers said that larger studies are needed, but that they envision the test as a potential screening tool for people at high risk for bladder cancer.
Traditional testing includes checking urine specimens for abnormal-looking cells, but that misses many cancers, Shay said.
An invasive test called cystoscopy is more definitive and involves inspecting the bladder through a catheter and removing suspicious cells.
Newer detection methods include testing urine for certain proteins, with results available while patients wait in the doctor's office.