Value of CYFRA 21–1,carcinoembryonic antigen, and squamous cell carcinoma antigen as tumor markers in non-small cell lung cancer patients

19042 Background: Non-small cell lung cancer (NSCLC) represents a major health burden in terms of incidence and mortality. Sensitive serum tumor markers are needed to identify early recurrence in post-surgical patients and monitor response to therapy. CYFRA 21–1 measures cytokeratin 19 fragments and has been reported as a sensitive tumor marker for NSCLC. We hypothesize that CYFRA 21–1 may complement other NSCLC markers including carcinoembryonic antigen (CEA) and squamous cell carcinoma antigen (SCCa). Methods: The CYFRA 21–1 assay is an automated immunochemiluminometric assay performed on serum. The assay utilizes KS19.1 and BM19.21 monoclonal antibodies in a standard sandwich format. Validation studies revealed favorable performance characteristics including limit of blank of 0.01 ng/mL, linearity from 0.1 to 100 ng/mL, and overall imprecision of < 4%. The upper 95th percentile reference limit was 1.5 ng/mL for healthy adult subjects. CEA and SCCa assays were performed using established immunoassay protocols, with upper reference limits of 3.0 and 2.2 ng/mL, respectively. Serum samples from 78 NSCLC patients were tested. Tumor histology within this group included adenocarcinoma (n=16) and squamous cell carcinoma (n=44) as well as a variety of other NSCLC types (n=18). Results: Our data show increasing sensitivity of CYFRA 21–1 with stage and in combination with CEA and SCCa (see table). Conclusion: Sensitive serum tumor markers for recurrent disease in NSCLC patients have the potential for significant clinical utility, as they may help optimize patient management. Biochemical evidence of recurrence would likely precede clinical signs and symptoms. Our data show that CYFRA 21–1 is complimentary to CEA and SCCa in a stage-dependent manner. While none of the markers performed well when used alone, a panel consisting of these three markers has high sensitivity and should be considered in the evaluation of NSCLC patients. Tumor marker positivity in NSCLC patients by stage Stage Number CYFRA 21–1 (%) CEA (%) SCCa (%) CYFRA 21–1 or CEA (%) CYFRA 21–1 or SCCa (%) CEA or SCCa (%) Any one of these three (%) I 46 30.4 43.5 21.7 58.7 39.1 54.3 67.4 II 12 50.0 75.0 0.0 75.0 50.0 75.0 75.0 III 12 66.7 58.3 41.7 91.7 83.3 75.0 100.0 IV 8 75.0 75.0 50.0 100.0 87.5 100.0 100.0 No significant financial relationships to disclose.