New Electrochemiluminescent Immunoassay for the Determination of CYFRA 21-1: Analytical Evaluation and Clinical Diagnostic Performance in Urine Samples of Patients with Bladder Cancer

Abstract

Background: A new electrochemiluminescent immunoassay (ECLIA) has been developed for the determination of cytokeratin 19 (CYFRA 21-1) in the Elecsys 2010 immunoassay system. Urinary CYFRA 21-1 might have a role in the diagnosis of bladder cancer. Methods: We performed an analytical evaluation of the CYFRA 21-1 ECLIA for serum and urine samples. The clinical value of urinary CYFRA 21-1 for the detection of bladder cancer was evaluated through its measurement in 226 urine samples from symptomatic and asymptomatic controls. Results: At concentrations of 2–30 μg/L, within-assay imprecision (CV) was below 2.1% for sera and 3.3% for urines, with interassay CVs below 3.3% for sera and 4.9% for urines. The day-to-day CV was <20% at concentrations >0.2 μg/L (functional sensitivity). Measurement of diluted samples showed that the assay estimated CYFRA 21-1 between 98% and 103% for sera and 98% and 105% for urines. Recovery of added CYFRA 21-1 was 99–105% for sera and 96–115% for urines. We separately compared serum and urine CYFRA 21-1 ECLIA results with those obtained with an IRMA (CIS bio international). Regression analysis for sera was: CYFRA 21-1 (ECLIA) = 0.520 + 1.018 CYFRA 21-1 (IRMA); [95% confidence interval (CI) (y-intercept), −0.260 to 1.309]; 95% CI (slope), 0.978–1.060; n = 100; Sy|x = 3.242; r2 = 0.987. For urine samples it was: CYFRA 21-1 (ECLIA) = 0.716 + 0.966 CYFRA 21-1 (IRMA); 95% CI (y-intercept), 0.009–1.422; 95% CI (slope), 0.956–0.976; n = 100; Sy|x = 4.136; r2 = 0.986. In urine samples voided by patients with and without bladder cancer, the best ROC analysis discrimination provided 81.0% (95% CI, 72.7–87.7%) sensitivity and 97.2% (95% CI, 90.2–99.6%) specificity at a threshold value of 5.7 μg/L. Conclusions: Our initial evaluation showed reliable analytical performance for urinary CYFRA 21-1, which might assist urologists in the detection of bladder cancer as a noninvasive adjunct to cystoscopy.

Evaluation of urine CYFRA 21‐1 for the detection of primary and recurrent bladder carcinoma

“…Previous studies showed that the CYFRA 21‐1 assay, which measures soluble fragments of cytokeratin 19 in the serum, can be applied to urine samples for the detection of bladder tumors. The sensitivity of the assay ranged between 64.8% 14 and 96.9%,18 and the specificity was between 67.2% and 97.2% 18, 20. The variability of the results can be attributed to different patient populations.…”

“…Only 12% of their patients had Grade 1 bladder tumors, and 32% of their patients had superficial (pTa) tumors, compared with 30% and 63% of the patients, respectively, in our study. Sanchez‐Carbayo and colleagues20 used an optimal cut‐off value of 5.7 μg/L and found a sensitivity of 81% in a group of 82 patients with bladder carcinoma. Only 27% of their patients had superficial (pTa) bladder carcinoma.…”

“…Pariente et al,18 along with other authors,16, 17 used first‐voided urine samples. El‐Ahmady and colleagues19 obtained a 24‐hour urine collection from each patient, whereas other investigators14, 20 used random urine samples. In one study, the assay was performed on uncentrifuged urine samples,14 and all of the other investigators centrifuged urine before storage.…”

“…The use of the CYFRA 21‐1 assay on voided urine samples has been examined by several investigators using different cut‐off points of cytokeratin 19 concentrations as a positive result. 14, 16–20 The results of the different studies have been variable. There is no consensus how urine samples should be obtained and stored.…”

Prognostic significance of preoperative serum CYFRA 21‐1 in patients with upper urinary tract urothelial carcinoma

“…2 The reliability of the CYFRA 21-1 assay has already been evaluated for bladder cancer detection purposes in urine samples. In a study by Sanchez-Carbayo et al, 4 CYFRA 21-1 had an overall sensitivity of 83.8%, with a sensitivity of 75%, 86.8%, 72.2% and 100% for Stage pTa, pT1, pT2 and pT3-T4, respectively. Pariente et al 5 noted that CYFRA 21-1 is a reliable tumor marker for bladder cancer diagnosis, with an overall sensitivity and specificity of 96.9% and 67.5%, respectively, using 4 ng/mL as the cut-off.…”