Clinicopathological features of intraoperative pleural lavage cytology for non-small cell lung cancer

Objective: The significance of clinicopathological features of pre- and post-resection pleural lavage cytology (PLC) for non-small cell lung carcinoma (NSCLC) currently remains unknown. Methods: Between January 2010 and December 2012, pre- and post-resection PLC were performed for NSCLC in 565 patients at Tohoku University, Miyagi Cancer Center, or Sendai Medical Center. The relationship between the clinicopathological features and patient outcomes was analyzed. Results: Twenty-two patients (3.9%) had positive findings from pre- or post-resection PLC. Both PLC were correlated with pT and pl factors, while only post-resection PLC was correlated with pN factor (p < 0.005). The 5-year disease-free survival (DFS) rate of the positive pre-resection PLC was significantly poorer than that of negative (26.7% vs. 76.9%, p < 0.0001). In addition, the 5-year DFS of the positive post-resection PLC was also poorer than that of negative (14.3% vs. 76.0%, p < 0.0001). Multivariate analyses revealed that both PLC were not independent prognostic factors in our study. Conclusions: A significant association of post-resection PLC with N factor is considered to be characteristics of post-resection PLC different from pre-resection PLC. A prognostic impact of post-resection PLC and its detailed difference from pre-resection PLC should be clarified by further investigations.