Assessment of serum CYFRA 21-1 in lung cancer

Cancer. 1996 Apr 1;77(7):1274-7. doi: 10.1002/(SICI)1097-0142(19960401)77:7<1274::AID-CNCR7>3.0.CO;2-I.


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.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Antigens, Neoplasm / blood
  • Biomarkers, Tumor / blood*
  • Carcinoembryonic Antigen / blood
  • Female
  • Humans
  • Immunoradiometric Assay
  • Keratins / blood*
  • Lung Neoplasms / blood*
  • Male
  • Middle Aged
  • Peptide Fragments / blood*
  • Phosphopyruvate Hydratase / blood
  • Sensitivity and Specificity
  • Serpins*


  • Antigens, Neoplasm
  • Biomarkers, Tumor
  • Carcinoembryonic Antigen
  • Peptide Fragments
  • Serpins
  • squamous cell carcinoma-related antigen
  • Keratins
  • Phosphopyruvate Hydratase