Lymphovascular invasion: A non-sized T descriptor for stage IA non-small cell lung cancer

Background Lymphovascular invasion (LVI) has not been included in the tumor-node-metastasis (TNM) staging manual of non-small-cell lung cancer (NSCLC). We aimed to investigate the predictive value of LVI on stage IA NSCLC and proposed a method of incorporating LVI into the T category based on the latest TNM staging manual. Methods The least absolute shrinkage and selection operator (LASSO)-penalized Cox multivariable regression model was performed to identify prognostic factors. The Kaplan-Meier method was used to compare overall survival (OS) and disease-free survival (DFS) between groups. Propensity score matching (PSM) was used to minimize bias. Results A total of 1452 eligible stage I NSCLC cases (stage IA without LVI, 1022 cases; stage IA with LVI, 120 cases; stage IB, 310 cases) were included. LASSO-penalized multivariable Cox analysis revealed that LVI was an independent prognostic factor for both OS and DFS. Survival analysis demonstrated that the survivals of stage IA NSCLCs without LVI were better than those of stage IA with LVI and stage IB NSCLCs. In the matched cohort, the survivals of stage IA NSCLCs with LVI were comparable to those of stage IB NSCLCs. Conclusions Stage IA NSCLCs with LVI and stage IB NSCLCs had similar survivals, and we proposed that LVI might be a non-sized T descriptor that upstaged stage IA diseases to stage IB.