The correlation of tertiary lymphoid structures with tumor spread through air spaces and prognosis in lung adenocarcinoma: focusing on pathological spatial features

Lung adenocarcinoma (LADC) exhibits high spatial heterogeneity, with distinct spatial variations in pathological features. The distribution of tertiary lymphoid structures (TLS) in LADC is uneven, and different TLS characteristics play unique roles. To investigate the correlation between TLS features and other pathological characteristics, particularly tumor spread through air spaces (STAS), we analyzed TLS and other pathological features on whole-slide images stained with HE and CD20/CD23. Additionally, the 14-Gene assay was used to assess prognostic risk. Among 388 enrolled LADC patients, 226 (58.2%) were TLS-positive. TLS showed a negative correlation with various adverse pathological features, with boundary-area TLS demonstrating the strongest correlation with STAS quantity (r= -0.324, P < 0.001). Multivariate Cox analysis identified boundary-area TLS as an independent prognostic factor for recurrence-free survival (HR = 0.856, 95% CI = 0.759-0.966, P = 0.026), while mature TLS was an independent factor for overall survival (HR = 0.841, 95% CI = 0.717-0.988, P = 0.035). High-density TLS at the tumor boundary was associated with low-risk stratification by the 14-Gene assay (P = 0.013). This study highlights the negative correlation between TLS and STAS, especially in boundary areas, and emphasizes the impact of tumor microenvironment spatial characteristics on clinical outcomes. Assessment of spatial heterogeneity in LADC facilitates precise risk stratification for patients.