Carcinoembryonic antigen in pleural effusion of patients with lung adenocarcinoma: a predictive marker for EGFR mutation

Background: Carcinoembryonic antigen CEA) can reflect tumor growth, recurrence and metastasis, and also predict the clinical efficacy of the epidermal growth factor receptor tyrosine kinase inhibitors EGFR-TKI). In the present study, we investigated the association between CEA in serum and pleural effusion PE) and EGFR mutations in patients with lung adenocarcinoma. Methods: We retrospectively investigated 114 lung adenocarcinoma patients with malignant pleural effusion MPE). CEA levels in serum and MPE were measured by immunoradiometric assay, we analysed the correlation between CEA and EGFR mutation status. Results: Fifty-three cases had EGFR mutation 46.5%). EGFR mutations were more common in females, patients with high levels of PE (>= 107.2 ng/mL) and serum CEA (>= 87 ng/mL). There was no significant difference in EGFR mutation rate between in tumor tissue and PE samples 49.3% vs. 41.9%, P=0.440). The result of receiver operating characteristic ROC) indicated that the cut off value of CEA in MPE was 107.2 ng/mL, which had the highest sensitivity SEN) and specificity SPE) for predicting EGFR mutation [SEN 66%, and SPE 62.3%, AUC =0.668, 95% confidence interval CI): 0.569-0.767, P=0.025]. The combination of gender, smoking history, serum and MPE CEA level had a higher calculated AUC 0.718, 95% CI: 0.622-0.813, P=0.000). Moreover, multivariate analysis showed that CEA level in MPE but not in serum was confirmed as the only independent factor associated with EGFR gene mutation status P=0.026) with an odds ratio of 2.885 95% CI: 1.137-7.317). Conclusions: MPE CEA can probably serve as a predictive marker for EGFR mutation in advanced lung adenocarcinoma. Combining gender, smoking history, and CEA has a relatively better predictive value. However, detecting EGFR mutations in lung adenocarcinomas is necessary for determining EGFR-TKI treatment in clinic.