Tertiary Lymphoid Structures Are Associated with Favorable Clinical Outcomes and Negatively Correlated with Cancer-Associated Fibroblasts in Esophageal Cancer

Background: Esophageal cancer remains a highly aggressive malignant tumor with poor prognosis, despite advances in combination therapies and novel immunotherapies. Tertiary lymphoid structures (TLSs), characterized by densely packed CD20+ B cells in a germinal-center-like structure, have recently been recognized as immune-stimulating components within the tumor microenvironment. In contrast, cancer-associated fibroblasts (CAFs) are stromal cells expressing fibroblast-activating protein (FAP) involved in immunosuppression. Methods: In this retrospective study, 124 clinical samples from patients who underwent radical surgery for esophageal cancer at our institute were analyzed. We investigated whether TLSs could serve as a prognostic factor and examined their association with tumor microenvironment factors. Results: The presence of TLSs was an independent prognostic factor for overall and progression-free survival in multivariate analyses. A high level of TLS formation correlated with better nutritional status, fewer M2 macrophages, and greater plasma cell infiltration. Additionally, little TLS formation was observed in areas with abundant CAFs, and quantitative analyses revealed a significant negative correlation between TLSs and CAFs. Conclusions: TLSs enhance antitumor immunity via macrophages and plasma cells and can be a valuable prognostic indicator in patients undergoing surgery for esophageal cancer. Targeting CAFs may prove to be a promising therapeutic strategy to enhance tumor-immunity-related TLSs.