Chronic pleural effusion one year after lung cancer surgery is associated with non-cancer mortality and postoperative nutritional decline.

OBJECTIVES

To evaluate the impact of postoperative chronic pleural effusion (CPE) at 1 year on long-term prognosis and host nutritional and physical status following anatomic resection for non-small cell lung cancer.

METHODS

This single-center retrospective study included 372 patients (2017-2021). CPE was defined as pleural fluid volume ≥80 mL on computed tomography scan at 1 year postoperatively, while no pleural fluid or pleural fluid volume <80 mL was defined as non-CPE. Inverse probability of treatment weighting (IPTW) was performed to adjust for preoperative baseline confounding factors between the two groups. The primary endpoint was overall survival. Secondary endpoints included cancer-specific death and changes in nutritional/physical indicators.

RESULTS

CPE was observed in 36 patients (9.7%), all of whom had demonstrated persistent effusion since 6 months postoperatively. In the IPTW-adjusted analysis, CPE was identified as an independent prognostic factor for poor OS (Hazard ratio 3.38; 95% confidence interval (CI), 1.57-7.26; p = 0.002). Competing-risk analysis revealed that CPE was a significant independent predictor of non-cancer death (Subdistribution HR 4.76; 95% CI, 1.56-14.41; p = 0.006), whereas no significant association was found with cancer-specific death. Analysis of non-cancer deaths showed that respiratory diseases, predominantly pneumonia, were the leading cause of death in the CPE group (9 of 12 patients, 75.0%). Weighted competing-risk analysis confirmed that CPE was a significant independent predictor specifically for pneumonia-related death (Subdistribution HR 5.26; 95% CI, 1.07-25.91; p = 0.041), with a 5-year weighted cumulative incidence of 11.89% in the CPE group versus 2.2% in the non-CPE group. Furthermore, patients with CPE exhibited significantly greater declines in Prognostic Nutritional Index (-4.1% vs 2.3%, p = 0.003), body weight (-5.4% vs -1.2%, p = 0.001), and Pectoralis Muscle Index (-11.5% vs -6.3%, p = 0.055) during the first postoperative year.

CONCLUSIONS

Postoperative CPE was identified as an independent risk factor for non-cancer death, especially pneumonia-related death, and was associated with significant nutritional and physical deterioration. These findings suggest that CPE represents a clinical indicator of systemic wasting and physiological decline rather than merely a local fluid retention.