Cytokeratin Tumor Marker Levels in Bronchial Washing in the Diagnosis of Lung Cancer

Abstract

The monitoring of serum concentrations of Cyfra 21-1, tumor polypeptide antigen (TPA), and tissue polypeptide specific antigen (TPS) has been demonstrated to be useful in the clinical treatment of patients with lung cancer. This study was planned to evaluate the clinical usefulness of the assay of these tumor markers on bronchial washing (BW) fluid and to compare it with serum assay in patients with neoplastic and nonneoplastic disease. Serum and BW fluid levels of Cyfra 21-1, TPA, and TPS were measured in 40 subjects (10 control subjects, 11 with chronic bronchitis, 10 with squamous cell lung cancer, and 9 with nonsquamous cell lung cancer) undergoing diagnostic bronchoscopy. BW was performed using 25 mL of pyrogen-free saline solution instilled through the working channel of the bronchoscope, and successively aspirated. The quantity of the fluid recovered was measured and used for the assay of albumin, Cyfra 21-1, TPA, and TPS. Mean BW concentrations of Cyfra 21-1, TPA, and TPS concentrations were significantly higher than serum concentrations (p < 0.01). Serum Cyfra 21-1, TPA, and TPS concentrations were significantly lower in controls and in those with chronic bronchitis than in patients with epidermoid and nonepidermoid carcinoma (p < 0.01). No difference in serum concentrations of the three markers was observed between controls and patients with chronic bronchitis. On the contrary, BW Cyfra 21-1 and TPA concentrations were significantly higher in those with chronic bronchitis and in cancer patients than in controls (p < 0.01), whereas they did not differ between patients with chronic bronchitis and cancer patients. No significant difference in BW TPS concentration was observed among the four groups. Sensitivity and specificity of the BW markers in diagnosing lung cancer were as follows: 68.4% and 61.9% for Cyfra 21-1; 68.4% and 66.6% for TPA; and 57.9% and 66.6% for TPS. BW fluid concentrations of Cyfra 21-1 and TPA are increased in patients with chronic bronchitis and in patients with lung cancer. Being unable to distinguish malignant from nonmalignant inflammatory conditions, the measurement of airway concentrations of such markers has a too-low specificity to be considered useful in diagnosing malignant abnormalities of the lung.