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Urinary beta-glucuronidase activity as an initial screening test for urinary tract malignancy in high risk patients.
1Department of Laboratory Medicine, National Taiwan University, Medical College, Taipei.
Background:
Routine urine cytology is not particularly useful as a screening test for urinary tract malignancy in the general population, due to its low detection rate. Bladder, ureteral, and pelvic lavage and flow cytometry increased the test sensitivity but could be applied only to a limited number of patients. A simple, sensitive screening test is needed.
Methods:
Two hundred eighty-two urine samples from 146 patients from the Urology Tumor Clinic patients during their initial visits were subject to cytologic evaluation and measurement of the activity of endogenous beta-glucuronidase, followed by confirmation procedures, including cystoscopy with biopsy, ultrasonography, radiography and/or computed tomography.
Results:
Among 146 patients, 32 had confirmed transitional cell carcinoma and 14 renal cell carcinoma. The urinary beta-glucuronidase activity was higher in patients with cancer than in those without cancer in the Urology Service and in 80 normal healthy control subjects. The accuracy of the urine enzyme diagnostic system measured by the receiver-operating characteristic (ROC) plot was 98% or higher based on the number of patients. The upper threshold value determined by ROC analysis was 1.7 nmol/min/mumol creatinine. At this threshold value, the sensitivities of the enzyme assay for transitional cell carcinoma, renal cell carcinoma, and all cancers were, respectively, 94%, 98%, and 95%. These values were much higher than the corresponding sensitivities of urine cytology: 41%, 0%, and 22%.
Conclusion:
Urinary beta-glucuronidase is a much more sensitive test to screen for urinary tract malignancy than routine urine cytology in high risk patients, provided that a positive test is followed by diagnostic procedures for confirmation.