Analytical and prospective evaluation of urinary cytokeratin 19 fragment in bladder cancer

Purpose: We evaluated CYFRA 21-1, an immunoradiometric assay, developed to detect solubleytokaratin 19 fragment, for its diagnostic performance in bla dder transitional cell carcinoma as well as its analytical performance. Materials and Methods: We assessed CYFRA 21-1 in the serum and urine of 182 patients, including 66 with bladder transitional cell carcinoma (group 1), 66 with another urological pathology (group 2) and 50 free of urothelial d isease (group 3). The power of urinary CYFRA as a diagnostic test for bladd er transitional cell carcinoma was evaluated by receiver operating characte ristics curve analysis. Analytical performance was assessed by determining intra-assay and interassay precision, and accuracy by dilution testing and recovery of supplemented analyte. Results: Mean urinary CYFRA plus or minus standard deviation was 154.39 +/- 49.00, 22.6 +/- 8.9 and 2.40 +/- 0.14 ng./ml. in groups 1 to 3, respective ly (significantly different). Receiver operating characteristics curve anal ysis revealed optimal 96.9% sensitivity and 67.2% specificity for a thresho ld value of 4 ng./ml. Analytical determination showed that intra-assay and interassay precision provides a satisfactory coefficient of variation. The assay for accuracy had acceptable recovery in diluted samples as well as in those with supplemented analyte. Conclusions: The urinary immunoradiometric CYFRA 21-1 assay performs well a nalytically. Urinary CYFRA 21-1 is a useful marker for diagnosing transitio nal cell carcinoma and provides sensitivity in low grade disease.