Abstract: Objective To investigate the expression of cytological examination and tumor markers in patients with lung cancer accompanied by pleural effusion, and their clinical significance, to provide a basis for the diagnosis of malignant tumors. Methods A total of 90 patients with lung tumors accompanied by pleural effusion who were treated at Taian Cancer Prevention and Treatment Hospital from June 2018 to June 2023 were selected for this study. All patients underwent cytological examination and tests for carcinoembryonic antigen (CEA), carbohydrate antigen 125 (CA125), carbohydrate antigen 19-9 (CA19-9), and neuron-specific enolase (NSE). According to the gold standard of pathological examination through surgery or biopsy, the 90 patients were divided into a benign lung tumor group(48 cases) and a lung cancer group (42 cases). The cytological detection rates, levels of tumor markers, and positive expression rates were compared between the two groups. The diagnostic efficacy of cytological examination of pleural effusion,tumor markers, and combined detection for malignant pleural effusion was compared using ROC curves. Results In the lung cancer group, the levels of CEA, CA19-9, NSE, and CA125 in pleural effusion were significantly higher than those in the benign lung tumor group,and the difference was statistically significant (P<0.05). All 90 patients with tumor-associated pleural effusion underwent cytological examination; among the lung cancer patients, tumor cells were detected in 32 out of 42 cases (76.19%), with 22 diagnosed upon the first submission and 10 diagnosed after two or more submissions, while the remaining 10 cases did not show tumor cells. No tumor cells were detected in the 48 patients with benign lesions. The combined detection showed the highest diagnostic value (area under the curve [AUC]=0.889), followed by tumor marker detection (AUC=0.767) and cytological detection (AUC=0.881)(P<0.05). Conclusion The combination of cytological examination and tumor markers in pleural effusion is more beneficial for the diagnosis of patients with lung cancer accompanied by pleural effusion.

Key words: lung cancer, cytological examination, pleural effusion, tumor markers