Mayo Clinic researchers have developed a new laboratory method for detecting recurring cancer of the bladder sooner and more accurately, according to a study published in The Journal of Urology.
The new detection method uses fluorescence in situ hybridization (FISH) to analyze cells in the urine for genetic changes characteristic of bladder cancer.
The double-blinded study compared the FISH detection method with urine cytology, currently the most commonly used test for detecting bladder cancer. The study involved the testing of 280 voided urine specimens from 200 males and 65 females.
"The FISH method detected cancerous cells in the urine of 81 percent of the patients with bladder cancer," said Kevin Halling, M.D., a Mayo Clinic pathologist and lead researcher on the study. "By comparison, urine cytology detected cancerous cells in only 57 percent of the patients with bladder cancer.
"Most importantly, the FISH test picked up more than 95 percent of the high grade cancers, which are the most dangerous and important group of bladder cancers because they have a high probability of progressing to potentially incurable muscle-invasive bladder cancer," says Dr. Halling. "With only one exception, the only cancers the test missed were low-grade tumors, which are less dangerous and have only a 3 to 5 percent chance of progressing to a higher stage tumor over five years."
The FISH test also detected recurrence of the cancer three to six months earlier than by the cytology, says Dr. Halling. This earlier detection capability should allow treatment to be initiated earlier and possibly give the patient a greater chance for survival, he said.
Approximately 50 percent of patients diagnosed with bladder cancer experience recurrence of the cancer within two years after their initial diagnosis. The high rate of recurrence requires patients to be closely monitored.
Mayo Clinic researchers collaborated with scientists from Vysis, Inc., in Downers Grove, Ill. to develop the FISH detection method.
About 53,000 new cases of bladder cancer are diagnosed annually in the United States, and about 10,000 people die of the cancer each year. Although the exact cause for bladder cancer is not known, people who smoke cigarettes are at the greatest risk of developing bladder cancer. Source: "A Comparison of Cytology and Fluorescence in Situ Hybridization for the Detection of Urothelial Carcinoma." The Journal of Urology. American Urological Association, Inc. Vol. 164, November 2000.
Darcie Prestegard
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Mayo Communications
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Journal
The Journal of Urology