Objective: No investigation has been conducted on the association between PET findings and serum Cyfra 21.1 and CEA levels in nonsmall cell lung cancers (NSCLC). The purpose of this study is to find out if the serum levels of Cyfra 21.1 and CEA are related to metabolic parameters by FDG PET in patients with NSCLC who had not received treatment.
Methods: Seventy-six NSCLC patients, who were admitted for initial staging by FDG PET/CT, were included in the study. Serum Cyfra 21.1 and CEA levels were assayed by enzyme-linked immunosorbent assay. FDG-PET images were analyzed with visual and quantitative methods. Standard uptake values (SUV), metabolic tumor volumes (MTV) and total lesion glycolysis were calculated for primary lesion (T) and whole-body lesions (primary and metastatic) (WB).
Results: Serum Cyfra 21.1 and CEA level was significantly higher in patients with locoregionally advanced disease (p < 0.05, p < 0.05, respectively) and metastatic disease (p < 0.01, p < 0.05, respectively) compared to those with localized disease. The serum ln-Cyfra-21.1 was significantly correlated with all volumetric tumor parameters (p < 0.001) and slightly with ln-SUVmean.WB (p < 0.05). There was no relationship between CEA levels and any PET metabolic parameters (p > 0.05). In multiple linear regression analysis incorporating ln-MTV.WB and ln-SUVmean.WB as independents, ln-MTV.WB correlated significantly and positively with ln-Cyfra-21.1 (β = 0.744, p < 0.001), whereas ln-SUVmean.WB did not significantly predict ln-Cyfra-21.1 (β = 0.019, p > 0.05).
Conclusion: This study demonstrates the existence of a significant relationship between total tumor burden and the serum Cyfra 21.1 level in NSCLC patients who had not received treatment. However, it requires further confirmation in operated NSCLC patients.