Cytokeratin markers in malignant pleural mesothelioma

Previously available serum tumor markers had a low clinical value in malignant pleural mesothelioma (MPM). The recently developed tissue polypeptide-specific antigen (TPS) and CYFRA 21-1 assays identify the soluble cytokeratin 18 and 19 fragments, respectively. In MPM these cytokeratins are expressed and may therefore be used as serum tumor markers. In this preliminary study, TPS and CYFRA 21-1 assays were evaluated to determine their potential for management of patients with MPM. Carcinoembryonic antigen (CEA) was evaluated as an additional marker. The study group consisted of 95 patients with benign lung and pleural diseases (BLPD), 14 patients with MPM, 41 patients with adenocarcinoma of lung (AC), and 40 patients with squamous cell carcinoma of lung (SQC). The utilized cutoff points corresponded to a 95% specificity for patients with BLPD. In MPM, TPS showed greater sensitivity (64.3%) than CYFRA 21-1 (50.0%), while CEA showed no sensitivity. In SQC, the marker CYFRA 21-1 had the highest sensitivity (52.5%), whereas in AC the most sensitive marker was CEA (56.1%). Significantly lower levels of CEA were found in MPM compared with BLPD (p < 0.001) or AC and SQC (p < 0.0001). Conversely, TPS levels in MPM were significantly higher than in SQC (p < 0.05). Close correlation of various individual pretreatment marker levels was observed only between TPS and CYFRA 21-1, both in MPM (r = 0.84; p < 0.001) and in non-small cell lung cancer (NSCLC) (r = 0.71; p < 0.001). In serial determinations of the markers during chemotherapy of MPM (n = 10), TPS and CYFRA 21-1 were shown to demonstrate more or less the same pattern of reactivity, although the changes in the TPS levels better reflected the clinical response to therapy. In conclusion, TPS seems to be a more sensitive marker than CYFRA 21-1.