Clinical Relevance of Intraoperative Pleural Lavage Cytology in Non-Small Cell Lung Cancer

Background: Intraoperative pleural lavage cytology for patients with lung cancer has been reported to be useful in detecting subclinical pleural dissemination. However, this procedure is not necessary for the staging of lung cancer in the current TNM staging system. Methods: Clinical records of 1025 patients with non-small cell lung cancer who underwent surgery were retrospectively reviewed and evaluated for the clinical relevance of intraoperative pleural lavage cytology. Results: Specimens of 37 patients (3.6%) were positive for pleural lavage cytology (PLC). Patients were categorized into three groups: positive PLC group, 27 patients with positive PLC without malignant pleural effusion or pleural dissemination; pleural dissemination (PD) group, 21 patients with malignant pleural effusion or PD; negative PLC group, 977 patients with negative PLC or negative PLC without PD. The positive PLC group had a significantly higher ratio of adenocarcinomas than the negative PLC group (p = 0.014). There was a significant difference in distribution of pleural factors between the positive and negative PLC groups (p < 0.001). Survival in the positive PLC group was significantly worse than in the negative PLC group (p = 0.007), especially in pathologic stage I (p = 0.001), but significantly better than in the PD group (p = 0.038). PLC status was found to be a significant independent prognostic factor in the multivariate analysis (p = 0.016). Conclusions: The present study demonstrates the clinical relevance of intraoperative PLC in early stage non-small cell lung cancer. The result of intraoperative PLC should be involved in the staging system of lung cancer.