Reduction of Serum Cytokeratin-3A9 is Associated with Chemotherapeutic Response in Patients with Non-Small Cell Lung Cancer

Background: Many tumor markers have been analyzed for applications in diagnosis, prognosis, and monitoring of cancer. Currently chemotherapy is routinely performed for patients with non-small cell lung cancer (NSCLC). The purpose of this study was to examine the serum tumor biomarker of cytokeratin (CK)-3A9 level in patients with NSCLC and its potential correlation with chemotherapeutic response. Methods: The serum samples of 196 NSCLC patients, 84 healthy controls, and 87 benign lung disease patients were provided for measurement of CK-3A9 and carcinoembryonic antigen (CEA). Serum CK-3A9 concentration was examined using a chemoluminescent method. The potential correlation between serum CK18-3A9 concentration and chemotherapeutic response was analyzed in 124 patients with advanced NSCLC (stages III and IV). Results: The serum CK-3A9 levels in NSCLC patients pre-chemotherapy were significantly higher than those of healthy controls and benign lung disease patients (p < 0.01). CK-3A9 was related to Union for International Cancer Control (UICC) stages (p < 0.01) and histological classification (p < 0.05), but not related to age, gender, smoking status, and chemotherapy regimen (all p > 0.05). The testing results of serum CK-3A9 levels showed a higher sensitivity than that for CEA (48.2% and 39.5%, respectively). The chemotherapeutic response in the 124 patients with advanced NSCLC included 0 complete response (CR), 50 partial response (PR), 65 no change (NC), and 9 progression disease (PD). Post-chemotherapy CK-3A9 levels were significantly decreased compared to pre-chemotherapy (p < 0.05). The serum CK-3A9 levels in patients who achieved PR declined significantly compared to those who did not respond (SD + PD) after 2 cycles chemotherapy (p <0.05). Conclusions: CK-3A9 appeared to be a new biomarker for reliable, cost-effective prediction of the efficacy of chemotherapy in patients with advanced NSCLC, although the results should be confirmed in larger studies.