Influence of pleural invasion on survival in pathologic T3-4N0M0 non-small cell lung cancer: a propensity score matching study based on the Surveillance, Epidemiology, and End Results database.

Background: Pleural invasion (PI) is considered to be an adverse prognostic factor in non-small cell lung cancer (NSCLC). However, the prognostic roles of PI in pathologic (p)T3-4N0M0 NSCLC remain controversial. Therefore, this study aimed to evaluate the predictive value of PI in patients with pT3-4N0M0 NSCLC.

Methods: This study selected 9,185 patients with resected pT3-4N0M0 NSCLC from 2010 to 2019 from the Surveillance, Epidemiology, and End Results (SEER) database. PL0 was defined as lack of PI; PL1 and PL2 as invasion of the elastic layer and of the surface of the visceral pleural invasion (VPI), respectively; and PL3 as the parietal pleura invasion (PPI). Patients were divided into six groups according to PI status and T categories. This study used propensity score matching (PSM) to reduce baseline differences. The risk factors were statistically analyzed using the Cox proportional hazard model. Overall survival (OS) was assessed with the Kaplan-Meier method and log-rank test.

Results: Kaplan-Meier analysis stratified by T category showed worse OS in patients with PI (P<0.001). In multivariable Cox analysis of OS, patients with T3 and VPI had a significantly worse prognosis than did those with T3 but not PI (after PSM: P=0.001). There was no difference between those with T3 and VPI and those with T3 and PPI (after PSM: P=0.12) or between those with T3 PI and those with T4 but not PI (after PSM: P=0.30).

Conclusions: PI is a factor of poor prognosis in patients with pT3-4N0M0 NSCLC. Our results recommend future studies exploring the prognostic value of various T3-4 subcategories to allow PI to be separated from other T descriptors and confounders.