Bladder cancer tests: What factors impact results?

February 16, 2016

Urology Times SUO internship program member Katie Murray, DO, reports on a study evaluating the differences in urine cytology and UroVysion FISH testing results among clinically meaningful patient subgroups.

Katie Murray, DOUT SUO 2015 Internship Member Profile

The results of urine tests for bladder cancer must be interpreted in the context of patient factors including age, gender, and smoking history, according to a study presented at the 2015 Society for Urologic Oncology annual meeting in Washington.

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Urine tests are often used to assist with diagnosis in patients undergoing a workup for hematuria by urologists. These tests are also used for follow-up in the patient population being followed over time following a diagnosis of bladder cancer.

Researchers from Duke University’s division of urology, Durham, NC wanted to evaluate the extent of differences in results of urine cytology and of UroVysion FISH testing (Abbott Molecular, Des Plaines, IL) among clinically meaningful patient subgroups. This phenomenon of variability across population subgroups is referred to as spectrum effects. The subgroups evaluated were defined by age, gender, smoking history, and race. According to the researchers, led by senior author Brant Inman, MD, MS, failure to acknowledge this heterogeneity may result in inappropriate interpretation and clinical decision making.

Using white light cystoscopy as the gold standard for diagnosis of bladder cancer or recurrence of disease, standard diagnostic test performance metrics were calculated for all patients and in the subgroups defined above. Pathologic diagnosis was not correlated, but instead only cystoscopic evaluation.

Over a 9-year time period, more than 4,000 pairs of cytology and cystoscopy were performed and nearly 1,700 pairs of UroVysion FISH and cystoscopy were performed. Subject-specific and population-averaged methodologies that take repeated observations into account were used to calculate test performance metrics for the entire cohort and the predetermined subgroups.

Next: What the authors found

 

Of those who had cystoscopy and cytology, 61% of the 990 patients were male and 75% were Caucasian. Smoking status included 9% current smokers, 45% former smokers, and 42% never smokers. For cytology, the sensitivity went up with increased age and specificity declined, with sensitivity around 48% for those age 40 years and up to 65% in those 80 years of age. Sensitivity of the test was also higher in males (65%) than females (45%). Smoking status did not have a major change in sensitivity and specificity for cytology when compared to cystoscopy.

Of those patients who had cystoscopy and UroVysion FISH, 59% of the 828 were males and 78% were Caucasian. Smoking status included 10% current smokers, 49% former smokers, and 41% and never smokers. For UroVysion FISH, increased age led to increased sensitivity up to 45% and decreased specificity to 70%. Higher sensitivity was found in current and former smokers near the 50% range compared to the 20% range for never smokers.

“The diagnostic performance of two widely used urine tests for bladder cancer, urine cytology and FISH, varied significantly according to the patient demographic in whom they were used, implying that there is no single sensitivity or specificity value that can summarize the performance of these tests,” the authors wrote.

They conclude that tests with high sensitivities could be preferentially chosen for high-risk populations such as current and former smokers. This information could also be used to avoid additional unnecessary procedures in elderly comorbid patients by using tests with high specificity and low sensitivity.

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