Visceral pleural invasion (VPI) indicates poor prognosis in non-small cell lung cancer (NSCLC), and is defined as a T2 descriptor for T1-sized tumor. However, whether its prognostic impact differs between pure-solid and part-solid tumors as preoperative diagnostic imaging is controversial. We aimed to elucidate the prognostic difference of VPI in cT1-sized NSCLC according to radiological tumor type (pure-solid or part-solid).
We retrospectively reviewed 498 NSCLC patients who underwent complete anatomical lung resection between 2009 and 2014. Patients with node-negative, cT1-sized (consolidation size, ≤ 3 cm) NSCLCs were included. VPI included pathological PL1 and PL2. The prognostic impact of VPI according to radiological tumor type was assessed using multivariate Cox regression analyses.
We evaluated 227 pure-solid and 271 part-solid tumors; median follow-up period was 57 months. VPI was found in 40 (17.6%) and 15 (5.5%) patients with pure-solid and part-solid tumors, respectively (p < 0.001). In pure-solid group, VPI patients showed significantly poorer overall survival (OS) rates than non-VPI patients (p = 0.003). In part-solid group, OS rates did not differ significantly according to VPI (p = 0.770). Multivariate analysis revealed that the adjusted hazard ratio (95% confidence interval) for poor OS was 2.129 (1.048-4.132, p = 0.037) for pure-solid tumors with VPI compared to pure-solid tumors without VPI, and 0.925 (0.050-4.920, p = 0.941) for part-solid tumors with VPI compared to part-solid tumors without VPI.
VPI had a negative prognostic impact on cT1-sized pure-solid tumors but not on part-solid tumors. Upstaging of the T-category by VPI in cT1-sized NSCLCs may be considered for pure-solid tumors.