New electrochemiluminescent immunoassay for the determination of CYFRA 21-1: analytical evaluation and clinical diagnostic performance in urine samples of patients with bladder cancer.
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 microg/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 microg/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; S(y|x) = 3.242; r(2) = 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; S(y|x) = 4.136; r(2) = 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 microg/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.
Sánchez-Carbayo
M
M
Laboratorio de Marcadores Tumorales, Servicio de Análisis Clínicos, Hospital General Universitario de Alicante, C/Maestro Alonso 109, 03010 Alicante, Spain.
Espasa
A
A
Chinchilla
V
V
Herrero
E
E
Megías
J
J
Mira
A
A
Soria
F
F
D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000097:blood / Q000652:urine*; D014408:Biomarkers, Tumor / Q000097:blood / Q000652:urine*; D002295:Carcinoma, Transitional Cell / Q000097:blood / Q000652:urine*; D004560:Electricity; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D053539:Keratin-19; D007633:Keratins; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D015203:Reproducibility of Results; D001749:Urinary Bladder Neoplasms / Q000097:blood / Q000652:urine*
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D053539:Keratin-19; C102012:antigen CYFRA21.1; D007633:Keratins