Prognostic significance of pleural lavage cytology in patients with lung cancer: a meta-analysis.

OBJECTIVE: Cytologic approaches such as pleural lavage cytology (PLC) are considered as possible aids to assessing prognosis of lung cancer patients. We aimed to comprehensively review the evidence for use of PLC to predict prognosis of lung cancer. METHODS: Fifteen studies, including 6391 patients, were found to be eligible for the present meta-analysis. A meta-analysis was done on the log hazard ratios and their variances in these studies. RESULTS: Four studies dealt with pleural lavage before lung resection, six studies dealt with pleural lavage after lung resection, and five studies had PLC data from both before and after lung resection examination. For before lung resection studies, combined hazard ratios showed that positive PLC results had an unfavorable impact on survival: 3.96 (95% confidence interval 2.48-6.33), 4.55 (2.95-7.04), 5.00 (3.39-7.36), 5.67 (3.81-8.43), and 7.06 (5.04-9.90), for 1-, 2-, 3-, 4- and 5-year, respectively. For after lung resection studies, combined hazard ratios showed that positive PLC results had an unfavorable impact on survival: 6.02 (3.74-9.71), 6.64 (4.53-9.72), 7.06 (4.93-10.12), 7.29 (5.18-10.25), and 8.47 (6.12-11.73), for 1-, 2-, 3-, 4- and 5-year, respectively. Totally, the combined hazard ratio was 5.61 (3.98-7.90), showing a worse survival when PLC was positive. These findings could be overestimated because of publication and reporting bias. CONCLUSIONS: PLC is a strong prognostic factor for survival in patients with lung cancer.