Prognostic Impact of Malignant Pleural Effusion at Presentation in Patients with Metastatic Non-Small-Cell Lung Cancer

Background: Despite its common occurrence, the influence of malignant pleural effusion (MPE) on the outcomes of patients with advanced non-small-cell lung cancer (NSCLC) with distant metastasis (M1b) is unknown. We evaluated the clinical characteristics associated with MPE at presentation and the prognostic impact of MPE at presentation in patients with stage M1b NSCLC. Methods: We extracted data from the Surveillance Epidemiology and End Results (SEER) registry from patients with NSCLC diagnosed between 2004 and 2005. Odds-ratio estimates were calculated using logistic regression, and the Kaplan-Meier method was used to estimate the overall survival. Cox proportional hazard model was used to evaluate whether MPE was an independent risk for outcome. Results: Among the 57,685 patients, MPE was present in 9170 (15.9%), including 3944 out of 31,506 (12.5%) without distant metastases and 5226 (20.0%) out of 26,179 with M1b. The probability of MPE was higher in patients with larger tumors, mediastinal lymph node involvement, and adenocarcinoma, NSCLC not otherwise specified, or large-cell histology. In patients with stage M1b, median overall survival (3 months versus 5 months), estimated 1-year survival (12.6% versus 24.8%), and 2-year survival (5.4% versus 11.3%) were significantly lower in patients with MPE compared with those without MPE (hazards ratio 1.49, 95% confidence interval 1.44-1.54, p < 0.0001). MPE was also an independent factor for worse survival in multivariate analysis (hazards ratio 1.36, 95% confidence interval1.30-1.43, p < 0.001). Conclusions: MPE is a common complication in patients with NSCLC and is associated with decreased survival in patients with distant metastases. If these data are validated, subsequent studies in patients with advanced NSCLC may consider stratification according to the MPE status.