Intraoperative rapid diagnosis of pleural lavage cytology in non-small cell lung cancer.

OBJECTIVE: Positive pleural lavage cytology (PLC +) is a poor prognostic factor for non-small cell lung cancer (NSCLC). However, data on the impact of intraoperative rapid diagnosis of PLC (rPLC) are lacking. Therefore, we evaluated the efficacy of rPLC before resection during surgery. METHODS: A total of 1,838 patients who underwent rPLC for NSCLC between September 2002 and December 2014 were studied retrospectively. We assessed the clinicopathological factors between rPLC findings and the impact on survival of patients with curative resection. RESULTS: The rPLC + status was observed in 96 (5.3%) among 1,838 patients. The rPLC + group had more unsuspected N2 (30%) than the rPLC- group (p < 0.001). The 5-year overall survival (OS) of patients who underwent lobectomy or more extensive resection with rPLC + , negative rPLC (rPLC-), and microscopic pleural dissemination (PD) and/or malignant pleural effusion (PE) were 67.3, 81.3, and 11.0%, respectively. In the rPLC + group, the prognosis of patients with pN2 was equal to that of pN0-1 (5-year OS: 77.9% vs. 63.4%, p = 0.263). Undetectable dissemination in the first evaluation immediately after starting surgery was found in 9% of rPLC + patients by additional evaluation of the thoracic cavity. CONCLUSIONS: Patients with rPLC + have more favorable survival than those with microscopic PD/PE after surgery. Curative resection should be performed in patients with rPLC + , even if N2 is detected during surgery. However, the rPLC + group often has N2 upstaging; therefore, systematic nodal dissection should be performed in rPLC + patients for exact staging. rPLC may contribute to preventing oversight PD by re-evaluation during surgery.