Visceral Pleural Invasion Is Not a Significant Prognostic Factor in Patients With a Part-Solid Lung Cancer

Background. Visceral pleural invasion (VPI) has been considered to be a prognostic factor. If a tumor shows VPI, it increases the T descriptor and upstages a tumor from stage IA to stage IB pathologically, even for those less than 30 mm in diameter. However, there is still some controversy regarding the prognostic significance of VPI in patients with radiologically early lung cancer with ground glass opacity. Methods. Between 2004 and 2012, 466 patients with surgically resected pathologic N0 non-small cell lung cancer less than 30 mm in diameter who showed a "part-solid" or "pure-solid" appearance on thin-section computed tomography scan were retrospectively reviewed. A Cox proportional hazard model was used to evaluate prognostic factors. Survival was calculated by the Kaplan-Meier method. Results. Two hundred thirty-seven patients (55%) showed part-solid and 209 (45%) showed pure-solid nodules on thin-section computed tomography scan. VPI was found in 24 (10%) part-solid nodules and 79 (38%) pure-solid nodules. On the basis of a multivariate analysis, VPI was not a significant prognostic factor in patients with part-solid nodules (p = 0.5902). In this group, the 5-year survival rates in patients with and without VPI were 85.6% and 94.9%, respectively (p = 0.3798). By contrast, VPI, vessel invasion, maximum tumor diameter, and carcinoembryonic antigen level were significant prognostic factors in patients with pure-solid nodules (p = 0.0211, 0.0188, 0.0372, and 0.0492, respectively). Moreover, the 5-year survival in patients with VPI (70.1%) was significantly worse than that in patients without VPI (81.3%) among patients with pure-solid nodules (p = 0.0051). Conclusions. VPI may not contribute to the prognosis of patients with part-solid nodules. Thus, upgrading of the TNM stage on the basis of VPI should be carefully considered in these patients. (C) 2014 by The Society of Thoracic Surgeons