Malignant cell count in pleural effusion: A potential indicator of mortality.

Background: The role of malignant cell count in pleural fluid as a potential predictor of survival remains under investigation. This study aims to assess the relationship between malignant cell count in pleural effusion and mortality in patients with malignant pleural effusion (MPE).

Methods: This retrospective cohort study was conducted at a tertiary referral and research hospital, including treatment-naive patients diagnosed with MPE. Univariate and multivariate Cox regression analyses were employed to identify independent predictors of mortality.

Results: A total of 63 patients were included in the analysis, with a male predominance (39 males, 61.9 %) and a mean age of 65.7 ± 12.5 years. The majority (76.2 %) of patients had NSCLC. Patients were stratified based on malignant cell count into two groups: those with <1700 cells/2mm² and those with ≥1700 cells/2mm². The two groups were similar in demographics, blood and pleural fluid parameters, and comorbidities. Multivariate Cox regression analysis revealed that male gender (HR: 4.14, 95 % CI: 1.65-10.39), active smoking (HR: 2.99, 95 % CI: 1.25-7.16), and malignant cell count (HR: 0.23, 95 % CI: 0.09-0.56) were independent predictors of mortality.

Conclusions: Our findings indicate that a malignant cell count of <1700 cells/2mm², male gender and active smoking are independent prognostic factors associated with increased mortality in patients with MPE. Further large-scale prospective studies are necessary to confirm the clinical relevance of cytological malignant cell counts and to explore the viability and functional significance of these cells.