Background and aims: The gold standard in malignant pleural effusion (MPE) diagnosis are closed pleural biopsy and thoracentesis, but their low positive rate despite high specificity necessitates additional tests, such as cytology or immunohistochemistry. Therefore, study aims to investigate the level of serum CEA, CA 15-3 and CA 19-9 with lung malignancy and malignancy related pleural effusion.

Methodology: A prospective observational study with a total of 50 patients were screen and collected from January 2022 until January 2023. Outcome were defined as MPE with lung cancer (MPELC), other organs cancer (MPEOO) associated with risk factors i.e., sociodemographic, comorbidity and level of the serum biomarker. p < 0.05 is determined as significance.

Result: A total of 18 patients and 6 patients with a confirmed case of MPE Lung CA, and MPE others organ. A significant association were found in MPELC with serum CEA, CA15-3, CRP. A multivariate analysis of MPELC and MPEOO with cofounding (demographic + comorbidity + laboratory measurement) in different models reported there were significant relationship of age, race, serum CEA and CA15-3 with MPELC. Study also reported the sensitivity and specificity of CEA=83.5%, CA19-9=55.8%, and CA15-3=73.5% compared to CRP=28.2%.

Conclusion: Our study shows that serum CEA, CA19-9 and CA15-3 were significantly associated with the lung cancer related exudative pleural effusion. However, further analysis with multicentred is needed to determine the validation of these biomarkers as diagnostic purposes.