Intraoperative pleural lavage cytology after lung resection as an independent prognostic factor for staging lung cancer.

Objective: Although malignant pleural effusion or dissemination is regarded as T4 per TNM classification of lung cancer, the prognostic significance in staging of pleural lavage cytologic examination remains undetermined. The purpose of this study was to clarify the utility of pleural lavage cytologic staging as a prognostic factor in patients with non-small cell lung cancer.
Methods: In 1271 patients with lung cancer who underwent curative resection, intraoperative pleural lavage cytologic examination was performed at thoracotomy (first cytologic examination), immediately after pulmonary resection and mediastinal lymph node dissection (second cytologic examination), and after last washing of pleural cavity (third cytologic examination). Positive first cytologic result represented cytologic positive result before lung resection; positive second and third cytologic results were regarded as cytologic positive results after lung resection.
Results: Eighty-nine patients (7.0%) had positive findings of pleural lavage cytologic examination before or after lung resection. Five-year survivals were 44.1% for patients with positive results before lung resection and 23.4% for patients with positive results after lung resection, both significantly worse than that for patients with negative results. Multivariate analyses revealed that positive lavage result after lung resection was an independent prognostic factor. We found significantly greater pleural recurrence among patients with positive pleural lavage cytologic results after lung resection than among those with negative results.
Conclusions: In addition to TNM classification, results of pleural lavage cytologic examination after lung resection should be considered when staging non-small cell lung cancer. Adjuvant systemic therapy may improve outcome for patients with positive results.