Prognostic value of visceral pleura invasion in non-small cell lung cancer.

OBJECTIVES The purpose of this study was to clarify the prognostic significance of visceral pleura invasion in T2 non-small cell lung cancer (NSCLC). MATERIALS AND METHODS Between 1990 and 2001, 439 consecutive patients with T2 NSCLC underwent curative surgical resection. The subjects included 234 patients with stage IB, 95 with stage IIB, and 110 with stage IIIA and B disease. The patients were divided into two groups according to the existence of visceral pleura invasion (group I without, group II with). Both groups were compared with regard to tumor size, histology, associated mediastinal lymph node involvement, and survival rates. RESULTS Visceral pleura invasion (group II) was identified in 114 patients (26%), and was present in 22% of patients with NSCLC with a tumor size of 3 cm or less and in 27% of those with a tumor larger than 3 cm (P=0.37). Visceral pleura invasion was associated with a higher frequency of mediastinal lymph node involvement (group I=22%, group II=34%, P=0.009). Five- and 10-year survival rates were 50 and 45% in group I, and 36 and 22% in group II (P=0.0006). In stage IB, visceral pleura invasion was identified in 53 patients (23%), and 5- and 10-year survival rates were 63 and 60% in the visceral pleura non-invasion group, and 44 and 28% in visceral pleura invasion group (P=0.0018). By multivariate Cox model analysis, age at intervention (relative risk=1.03, P=0.0017), N status (relative risk=1.53, P<0.0001), tumor size (relative risk=1.83, P=0.0452) and visceral pleura invasion (relative risk=1.42, P=0.0291) were independent predictors of poor prognosis. CONCLUSIONS We were able to demonstrate that visceral pleura invasion was a factor of poor prognosis in T2 NSCLC. It was found to correlate with more extensive mediastinal lymph node involvement and a decreased survival rates. Therefore, the patients with visceral pleura invasion should be closely followed up especially.