CEA , AFP , CA 125 , CA 153 and CA 199 in Malignant Pleural Effusions Predict the Cause

Determination of the cause of malignant pleural effusions is important for treatment and management, especially in cases of unknown primaries. There are limited biomarkers available for prediction of the cause of malignant pleural effusion in clinical practice. Hence, we evaluated pleural levels of five tumor biomarkers (CEA, AFP, CA125, CA153 and CA199) in predicting the cause of malignant pleural effusion in a retrospective study. Kruskal-Wallis or Mann-Whitney U tests were carried out to compare levels of tumor markers in pleural effusion among different forms of neoplasia - lung squamous cell carcinoma, adenocarcinoma, or small cell carcinoma, mesothelioma, breast cancer, lymphoma/leukemia and miscellaneous. Receiver operator characteristic analysis was performed to evaluate sensitivity and specificity of biomarkers. The Kruskal-Wallis test showed significant differences in levels of pleural effusion CEA (P<0.01), AFP (P<0.01), CA153 (P<0.01) and CA199 (P<0.01), but not CA125 (P>0.05), among the seven groups. Receiver operator characteristic analysis showed that, compared with other four tumor markers, CA153 was the best biomarker in diagnosing malignant pleural effusions of lung adenocarcinoma (area under curve (AUC): 0.838 (95%confidence interval: 0.787, 0.888); cut-off value: 10.2U/ ml; sensitivity: 73.2% (64.4-80.8)%, specificity: 85.2% (77.8-90.8)%), lung squamous cell carcinoma (AUC: 0.716 (0.652, 0.780); cut-off value: 14.2U/ml; sensitivity: 57.6% (50.7-64.3)%, specificity: 91.2% (76.3-98.0)%), and small-cell lung cancer (AUC: 0.812 (0.740, 0.884); cut-off value: 9.7U/ml; sensitivity: 61.5% (55.0-67.8)%, specificity: 94.1% (71.2-99.0)%); CEA was the best biomarker in diagnosing MPEs of mesothelioma (AUC: 0.726 (0.593, 0.858); cut-off value: 1.43ng/ml; sensitivity: 83.7% (78.3-88.2)%, specificity: 61.1% (35.8-82.6)%) and lymphoma/leukemia (AUC: 0.923 (0.872, 0.974); cut-off value: 1.71ng/ml; sensitivity: 82.8% (77.4-87.3)%, specificity: 92.3% (63.9-98.7)%). Thus CA153 and CEA appear to be good biomarkers in diagnosing different causes of malignant pleural effusion. Our findings implied that the two tumor markers may improve the diagnosis and treatment for effusions of unknown primaries.


Introduction
In China, malignant disease involving the pleura is the second leading cause of pleural effusions (PEs) after tuberculosis.A study showed that, at Beijing, 49.6% of 668 PEs were due to Mycobacterium tuberculosis infection, malignancy accounting for 24.7% (Sun, 2011).Currently, Lung cancer and breast cancer account for 50-65% of malignant pleural effusions (MPEs).Lymphomas, tumors of the genitourinary tract and gastrointestinal tract account for a further 25%.Causes of unknown primary (CUP) are responsible for 7-15% of all malignant pleural effusions (Roberts et al., 2010).
To determine the cause of MPE is important for treating and managing MPE.Firstly, the most important factor influencing the life expectancy in patients with MPEs is the source of the tumor.The shortest survival time is observed in MPEs secondary to lung cancer and the organ and have the advantage for the determination of the origin.Some markers were classified as oncofetal antigens, such as carcinoembryonic antigen (CEA), alphafetoprotein (AFP).Some markers classified as tumor associated antigens are produced by various organs and are not specific to cancer but associated with cancer, such as, cancer antigen (CA) 125, CA153, CA199 (Watanabe, 1996;Malati, 2007).Now, levels of pleural effusion CEA, AFP, CA125, CA153 and CA199 have been assayed in many studies focusing on differentiating benign and malignant pleural effusions (Botte et al., 1990;Cascinu et al., 1997;Porcel et al., 2004;Shitrit et al., 2005;Gaspar et al., 2008;Liang et al., 2008).But there is as yet no evidence that PE tumor markers were employed in predicting the cause of MPE.
In this study, we aimed to measure levels of five PE tumor markers in patients with different causes of MPEs and evaluated their diagnostic values in differentiation of different causes of MPEs.

Subjects
This study has been conducted by the Department of Lab Medicine, Shandong Provincial Chest Hospital, Jinan, Shandong Province.The study protocol was approved by the Ethical Committee of the Shandong Provincial Chest Hospital.Written informed consent was not required because of the retrospective nature of the investigation.Between August 2010 and June 2013, patients who accepted PE tumor markers measurements were enrolled in this retrospective study.Subsequently, the patients were included if they met the following criteria: the examinations of PE or biopsy specimens revealed underlying malignancy; primary tumors were confirmed histologically.

Sample collection and analysis
All PE samples were collected before any treatment was initiated within 24 h after hospitalization.PEs were centrifuged at 4˚C 1200 r/min for 15min, and the supernatants were processed for analyzing CEA, AFP, CA125, CA153 and CA199 on UniCel DxI 800 immunoassay system (Beckman Coulter, Brea, CA).

Statistical analysis
Statistical analysis was carried out using SPSS

Results
Of 286 PEs studied, 35 were excluded due to unknown primary origin, and the remaining 251 PEs were included in our study.All patients were hospitalised.The study population had a mean age of 58.25±13.77years (range 5 to 89 years), and 58.6% were male.Table 1 presents the mean age, sex and other characteristics of every evaluated group.It showed that lung adenocarcinoma (128 cases, 60.0%) was the main cause of malignant pleural effusions, followed by lung squamous cell carcinoma (34 cases, 13.5%), miscellaneous tumors (30 cases, 12.0%), mesothelioma (18 cases, 7.2%), small-cell lung cancer (17 cases, 6.8%), lymphoma/leukemia (13 cases, 5.2%) and breast cancer (11 cases, 4.4%).

Diagnostic performance of tumor markers in differentiation of different causes of MPEs
The capacity of tumor markers to differentiate causes of MPEs was assessed with operating characteristic curve analysis.The under curve (AUC) when tumor markers were used to differentiate causes of MPEs was presented in Table 3

Discussion
To determine the cause of malignant pleural effusion (MPE) is important for treating and managing MPEs.In this study, we measured levels of five PE tumor biomarkers (CEA, AFP, CA125, CA153 and CA199) for differentiating causes of MPEs.Our data showed that significant difference existed in levels of PE CEA (P<0.01),AFP (P<0.01),CA153 (P<0.01) and CA199 (P<0.01)among the seven groups of MPE patients, except CA125 (P>0.05).ROC analysis showed that, CA153 was the best biomarker in diagnosing MPEs of lung adenocarcinoma, lung squamous cell carcinoma, and small-cell lung cancer; CEA was the best biomarker in diagnosing MPEs of mesothelioma and lymphoma/ leukemia.These data implied that PE CA153 and CEA can be used to predict the cause of MPE, the two markers would improve to find primary tumor in CUP cases.
The new clinical practice guidelines published by ESMO for the diagnosis, treatment and follow-up of cancers of unknown primary site set out what you need to know in order to manage these patients (Pavlidis et al., 2010).They point out that it is essential to differentiate clinical and pathological subsets of CUP.Light microscopy is the traditional method for MPE diagnosis, but an adequate sample of tumor tissue is essential.Immunocytochemistry is an adjunct to the cytological diagnosis of metastatic carcinomas in MPE (Pomjanski et al., 2005;Zhu et al., 2007;Bocking et al., 2009;Elstrand et al., 2009;Liu et al., 2012).Molecular profiling is very useful (Davidson et al., 2007;Cheng et al., 2008;Jiang et al., 2008;Pu et al., 2008;Liu et al., 2012), it may aid in the diagnosis of the putative primary tumor site in some patients.However, their impact on patient outcome via administration of primary site-specific therapy remains questionable and unproven in prospective trials.Endoscopy is sometimes useful, but not in all patients.Its use should be guided by specific symptoms or signs.For example, ENT panendoscopy (cervical node involvement), bronchoscopy (positive chest X-ray or CT scan with a cough).In terms of imaging, a routine chest radiograph is part of the initial evaluation of the patient with CUP.CT scan and MRI are useful, especially in the detection of primary breast tumors.A recent meta-analysis   .2014.15.1.363 CEA, AFP, CA125, CA153 and in Malignant Pleural Effusions Predict the Cause (Kwee et 2009) showed that, overall, FDG-PET/CT was able to detect 37% of primary tumors in patients with CUP, with both sensitivity and specificity of 84%.On the other hand, it should be realized that FDG-PET/CT is an expensive examination, and false-positive FDG-PET/CT findings may result in unnecessary additional invasive diagnostic procedures, which have associated morbidities and costs (Kwee et al., 2008).Based on these problems, tumor markers may be the efficient, cost-effective diagnostic alternative method in differnetiating causes of MPEs, including CUP.Now, there was very little evidence about the use of tumor markers in the diagnosis of primary tumors in CUP patients.Patients with CUP should have serum human chorionic gonadotropin β (β-HCG), AFP and prostatespecific antigen (PSA) tested (in men) to exclude treatable extragonadal germ-cell tumors and to identify metastatic prostate cancer amenable to endocrine treatment (Losa Gaspa et al., 2002;Tsukushi et al., 2006;Destombe et al., 2007).High levels of serum thyroglobulin in CUP patients with bone metastases suggest an occult thyroid cancer.Serum CA153 and CA125 could be of some help, i.e. in isolated axillary node adenocarcinomas and in peritoneal papillary adenocarcinomatosis, respectively.In all other cases, routine evaluation of commonly used epithelial serum tumor markers (CEA, CA199, CA 153, CA125) has no proven prognostic or diagnostic value, and non-specific elevations of multiple markers occurs in the majority of CUP patients (Panza et al., 1987;Pavlidis et al., 1994).Currently, there are few studies on PE tumor markers in detection of CUP, meanwhile, few tumor markers are evaluated in diagnosing different causes of MPEs.So, this retrospective study was performed and aimed to compare levels of PE tumor markers between different causes of MPEs.ROC analysis showed the good performance of tumor markers in differentiation of MPEs.According to our data, PE tumor marker offered an efficient, cost-effective diagnostic alternative method in differential diagnosis of causes of MPEs.
The results of this study must be interpreted with caution because of its retrospective nature.Since our hospital was a tuberculosis referral hospital in China, the disease spectrum in this study was not similar like other reports (Cellerin et al., 2008;Roberts et al., 2010), the disease spectrum can directly affect PE tumor markers' diagnostic parameters (AUC, sensitivity and specificity) in differentiating causes of MPEs.Meanwhile, in some groups (such as, breast cancer, mesothelioma, smallcell lung cancer and lymphoma/leukemia), number of evaluated cases were small.Hence, a future approach will be to analyze levels of PE tumor markers in a prospective larger cohort of samples to ascertain their levels in MPE patients and therefore to validate their suitability as candidate biomarkers in differentiating MPEs.
In conclusion, we have demonstrated that CA153 and CEA can be used to differentiating causes of MPEs, such as, lung adenocarcinoma, lung squamous cell carcinoma, small-cell lung cancer, mesothelioma and lymphoma/ leukemia.We believe our findings would aid to find the primary tumor in CUP cases.In the future, a prospective larger cohort study needs to be performed to ascertain levels of PE tumor markers in MPE patients and therefore to validate their suitability as candidate biomarkers in differentiating causes of MPEs.