title: Assessment of serum CYFRA 21-1 in lung cancer.
abstract: BACKGROUND
  Cytokeratins are the intermediate filaments of the cytoskeletal protein located in normal epithelia, tumor, and cultured cells. Recently, a fragment of cytokeratin subunit 19, referred to as CYFRA 21-1, detected in the serum of patients with nonsmall cell lung cancer, has been reported as a new tumor marker. This article reports the results of a study of serum fragment CYFRA 21-1, measured by immunoradiometric assay, as a marker of lung cancer.
  
  
  METHODS
  One hundred fourteen patients with primary lung cancer, 6 patients with malignant solid tumor, 116 patients with a variety of benign diseases, and 29 normal individuals were entered into the study. Serum CYFRA 21-1 levels were obtained by means of immunoradiometric assay using the CYFRA 21-1 EIA (enzyme immunoassay) kit. In addition, we studied other tumor markers, including carcinoembryonic antigen (CEA), squamous cell carcinoma antigen (SCC), and neuron specific enolase (NSE), as a means of lung cancer diagnosis.
  
  
  RESULTS
  The diagnostic accuracy and sensitivity of serum CYFRA 21-1 for the detection of lung cancer were highest among the four markers. The serum CYFRA 21-1 levels were most highly elevated in lung carcinoma patients (in particular UICC Stage IV patients) across different histologic types and attained 85.1% sensitivity when using a threshold of 3.5 ng/mL. The diagnostic sensitivity for detecting lung carcinoma was substantially enhanced by means of combined assays of CYFRA 21-1 with CEA overall for lung cancer, with SCC for squamous cell carcinoma, and with CEA for adenocarcinoma.
  
  
  CONCLUSIONS
  These findings suggest that serum assays of CYFRA 21-1 are clinically useful for the diagnosis of lung carcinoma.
authors.affiliation: Fourth Department of Internal Medicine, Kinki University School of Medicine, Osaka, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Muraki
authors.forename: Y
authors.initials: Y
authors.lastname: Tohda
authors.forename: T
authors.initials: T
authors.lastname: Iwanaga
authors.forename: H
authors.initials: H
authors.lastname: Uejima
authors.forename: Y
authors.initials: Y
authors.lastname: Nagasaka
authors.forename: S
authors.initials: S
authors.lastname: Nakajima
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood*; D002272:Carcinoembryonic Antigen / Q000097:blood; D005260:Female; D006801:Humans; D015592:Immunoradiometric Assay; D007633:Keratins / Q000097:blood*; D008175:Lung Neoplasms / Q000097:blood*; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood*; D010751:Phosphopyruvate Hydratase / Q000097:blood; D012680:Sensitivity and Specificity; D015843:Serpins
chemical_list: D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002272:Carcinoembryonic Antigen; D010446:Peptide Fragments; D015843:Serpins; C051072:squamous cell carcinoma-related antigen; D007633:Keratins; D010751:Phosphopyruvate Hydratase