Head-to-head comparison of serum and urine cytokeratin-19 fragments (CYFRA 21–1) for bladder cancer diagnosis

Background: Some studies have investigated the diagnostic accuracy of cytokeratin-19 fragments (CYFRA 21-1) for bladder cancer, but no study has compared the diagnostic accuracy of serum and urine CYFRA 21-1 in a head-to-head manner. The aims of this study were to (I) compare the diagnostic accuracy of serum and urine CYFRA 21-1 and (II) investigate whether the diagnostic accuracy can be improved if serum and urine CYFRA 21-1 were used together. Methods: In this prospective study, we enrolled patients with bladder cancer symptoms that were admitted to our hospital between January 1, 2016, and December 31, 2016. Serum and urine CYFRA 21-1 were detected using a Maglumi 2000 Plus immunoassay analyser. The diagnostic accuracy of the serum and urine CYFRA 21-1 was assessed using a receiver operating characteristic (ROC) curve analysis and multivariable logistic regression. Results: A total of 234 subjects were enrolled in the study, 152 with bladder cancer and 82 with non-bladder cancer. The areas under the ROC curve (AUCs) for serum and urine CYFRA 21-1 were comparable (0.74 vs. 0.74, P=0.91). The AUC for the serum and urine CYFRA 21-1 combination was 0.83, which was significantly higher than that of the serum (P=0.04) and urine (P=0.03) CYFRA 21-1 alone. Conclusions: Both the serum and urine CYFRA 21-1 have comparable diagnostic accuracy for bladder cancer. The diagnostic accuracy can be improved if the serum and urine CYFRA 21-1 are used together.