This is a multicenter retrospective study that collected diagnostic information of patients with pleural effusion. The overall survival (OS) time of malignant patients was followed up, defined as the time from diagnosis to death. Clinical data and residual pleural effusion specimens were collected from patients. Metabonomics was utilized to differentiate between benign and malignant pleural effusion and to evaluate the prognosis of lung cancer patients with malignant pleural effusion.

Pleural effusion (PE) is a common yet challenging problem in clinical settings. PE is a symptom caused by over 50 diseases and is typically classified as either malignant pleural effusion (MPE) or benign pleural effusion (BPE). MPE affects a significant number of individuals, with an estimated annual incidence of 500-700 cases per million population. Metastatic cancer is the leading cause of MPE, and lung cancer accounts for approximately 37.5% of cases. The management of MPE is a major clinical challenge due to its association with a typically poor prognosis, with a median survival of only 3 to 12 months. However, predicting survival in MPE patients can be difficult due to significant heterogeneity in underlying malignancy and patient performance status. Therefore, accurate prognostication remains a significant challenge in the management of MPE.

Metabonomics is an analytical technique for detecting metabolites in biological samples and has been widely used in disease diagnosis and prognosis evaluation in recent years. The aim of this study is to use Metabonomics technology to compare and analyze the differences in metabolites between benign and malignant pleural effusion, and to explore its application in the prognosis evaluation of lung cancer patients with malignant pleural effusion.

Inclusion Criteria:

• 18 Years to 80 Years; detection of pleural effusion by chest computed tomography, radiography, or ultrasonography; pathologically confirmed lung cancer in pleural effusion.

Exclusion Criteria:

• pleural effusion not caused by lung cancer or of unknown origin; other concurrent malignant diseases; incomplete information; lack of any follow-up data.

patients with pleural effusion