An Open Source Automated Tumor Infiltrating Lymphocytes Algorithm for Prognosis in Primary Small Bowel Adenocarcinoma Using Routine Hematoxylin and Eosin Stained Sections.

OBJECTIVE: While tumor-infiltrating lymphocytes (TILs) are prognostic in various cancers, their role in small bowel adenocarcinoma (SBA) is unexplored. This study evaluates the prognostic significance of digitally quantified TILs in SBA. METHODS: Using digital pathology (QuPath) on hematoxylin and eosin (H&E)-stained slides from 62 SBA cases, we quantified tumor cells, TILs (lymphocytes & plasma cells), and stromal components. Derived variables (eTILs, etTILs, esTILs, eaTILs, sTILs, iTILs, easTILs, and tumor-stroma ratio [TSR]) were correlated with clinicopathological features and survival. To account for multiple comparisons across all statistical tests, false discovery rate (FDR) correction was applied. RESULTS: Several TIL-related parameters showed suggestive associations with clinicopathological features (p < 0.05), though none remained significant after FDR correction. In univariate survival analysis, M stage and TNM stage were strongly associated with disease-free survival (DFS) and remained highly significant after FDR correction (both q < 0.001). Regarding TIL-related parameters, higher eTILs (p = 0.028) and iTILs (p = 0.032) showed suggestive associations with prolonged overall survival (OS) in univariate analysis, and higher iTILs also showed a suggestive association with DFS (p = 0.045); however, none of these associations remained significant after FDR correction. In multivariate analysis, M stage and TNM stage were confirmed as independent prognostic factors for DFS, while eTILs (p = 0.099) and tumor deposit (p = 0.055) showed trends toward independent prognostic significance without reaching statistical significance. CONCLUSION: This study, for the first time, objectively quantifies TILs in SBA, a rare tumor, using digital pathology and explores the potential prognostic significance of TILs in SBA. TIL-related parameters demonstrate suggestive trends that warrant validation in larger, independent cohorts. These findings provide a foundation for future studies to clarify the role of TILs in SBA.