title: Performance characteristics of an automated assay for the quantitation of CYFRA 21-1 in human serum.
abstract: OBJECTIVE
  A fragment of cytokeratin 19, CYFRA 21-1, has been reported to be a sensitive tumor marker for non-small cell lung cancer (NSCLC). We describe analytical performance characteristics of a novel CYFRA 21-1 assay and hypothesize that CYFRA 21-1 complements the clinical sensitivity of carcinoembryonic antigen (CEA) and squamous cell carcinoma antigen (SCCa).
  
  
  METHODS
  Performance characteristics of a CYFRA 21-1 immunochemiluminescent assay included analytical sensitivity, imprecision, linearity, analyte stability, and reference interval determination. Ninety-two pretreatment NSCLC serum samples were tested for CYFRA 21-1, CEA, and SCCa. Sensitivity was determined for each marker individually and in combination, with regard to tumor stage and histology.
  
  
  RESULTS
  The analytical sensitivity was 0.01 ng/mL. Total imprecision ranged from 4.0 to 6.3% at 4.9 to 28.4 ng/mL, respectively. The assay was linear from 0.9 to 71.4 ng/mL (slope=0.995, intercept=-0.60, r(2)=0.999). CYFRA 21-1 was stable for 48 h at ambient temperature and 14 days at 4°C. The 97.5th percentile of a reference population was 1.9 ng/mL. Across disease stage, the sensitivities of CYFRA 21-1, CEA, and SCCa were 17-81%, 30-52%, and 24-39%, respectively. CYFRA 21-1 combined with CEA or SCCa increased sensitivity above that of any single marker.
  
  
  CONCLUSIONS
  An immunochemiluminescent assay for CYFRA 21-1 had favorable performance characteristics. CYFRA 21-1 was complementary to CEA and SCCa and increased clinical sensitivity in patients with NSCLC.
authors.affiliation: Department of Pathology, University of Utah School of Medicine, Salt Lake City, UT 84112, USA.
authors.forename: Jay L
authors.initials: JL
authors.lastname: Patel
authors.forename: J Alan
authors.initials: JA
authors.lastname: Erickson
authors.forename: William L
authors.initials: WL
authors.lastname: Roberts
authors.forename: David G
authors.initials: DG
authors.lastname: Grenache
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood; D002272:Carcinoembryonic Antigen / Q000097:blood; D002289:Carcinoma, Non-Small-Cell Lung / Q000097:blood; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D053539:Keratin-19 / Q000097:blood*; D057230:Limit of Detection; D008163:Luminescent Measurements / Q000379:methods*; D008175:Lung Neoplasms / Q000097:blood; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D015843:Serpins / Q000097:blood
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D053539:Keratin-19; D015843:Serpins; C102012:antigen CYFRA21.1; C051072:squamous cell carcinoma-related antigen