Bladder cancer detection with CT urography in an Academic Medical Center.

In a large, retrospective study evaluating CT urography for the detection of bladder cancer compared to the gold standard cystoscopy, Sadow and associates demonstrate that current CT urography has the potential to become a screening test for bladder cancer but lacks the sensitivity required to replace cystoscopy at this time.

Since many believe that cystoscopy is an expensive and uncomfortable method of screening patients with hematuria for bladder cancer, many investigators have explored various imaging modalities, such as intravenous pyelogram {1} and ultrasound {2}, and their ability to detect bladder cancer with little success. With the advent of improved CT technology, many groups have investigated using CT urography to detect bladder cancer since it has become the preferred method to screen for upper urinary tract causes of hematuria. This study uses a retrospective approach in a large population of 838 patients with hematuria or previous history of bladder cancer, comparing CT urography and cystoscopy. According to the results, CT urography had an overall sensitivity and specificity of 78.5% and 94.2%, respectively, compared to cystoscopy, which had a sensitivity and specificity of 95.3% and 92%. CT urography had a greater sensitivity in patients evaluated for gross hematuria (83.3%) compared to microscopic hematuria (42.9%). Compared to cystoscopy, CT urography had a lower sensitivity (77.8% versus 95.1%) in detecting recurrent bladder tumors in patients with prior history of bladder cancer. Both cystoscopy and CT urography had a high negative predictive value of 98.9% and 95.3%, respectively, and a low positive predictive value of 72.1% and 74.5%. This is the largest retrospective study examining CT urography compared to cystoscopy to detect bladder cancer. In another retrospective study, Sudakoff found that the sensitivity of CT urography was 64% in 400 patients with gross or microscopic hematuria {3}. Two prospective studies, each with 118 and 200 patients, found that CT urography had higher sensitivities of 93% when screening patients with gross hematuria {4,5}. These studies were promising, but the numbers of bladder cancers detected were too low to draw any definitive conclusions. This article by Sadow and associates is the strongest retrospective study comparing CT urography to cystoscopy, and the only one that looked at patients with a prior diagnosis of bladder cancer. Although CT urography remains promising as a potential screening tool for bladder cancer, this study shows that the sensitivity in patients presenting with gross hematuria or prior history of bladder cancer is not sufficiently high to replace cystoscopy. Another disadvantage of using CT urography as a screening tool is the cost and need for intravenous contrast, which has potential risks for patients and excludes patients with lower glomerular filtration rates. In the future, larger prospective trials are needed to fully evaluate CT urography as a screening tool to diagnose bladder cancer which will most likely improve as technology improves.

References: {1} Corrigan et al. BJU Int 2000, 85:806-810 [PMID:10792157]. {2} Datta et al. Ann R Coll Surg Engl 2002, 84:203-205 [PMID:12092877]. {3} Park et al. Radiology 2008, 245:798-805 [PMID:17951346]. {4} Sudakoff et al. J Urology 2008, 179:862-867 [PMID:18221955]. {5} Turney et al. BJU Int 2006, 98:345-348 [PMID:16879676].