Prognostic implications of tumor-infiltrating lymphocytes in association with programmed cell death ligand 1 expression in remnant gastric cancer.

Objective: Remnant gastric cancer (RGC) is usually associated with a worse prognosis. As they are less common and very heterogeneous tumors, new prognostic and reliable determinants are required to predict patients' clinical course for RGC. This study aimed to investigate the tumor-infiltrating lymphocytes (TILs) and programmed cell death ligand 1 (PD-L1) status as prognostic biomarkers in a cohort of patients with RGC to develop an immune-related score. Methods: Patients with gastric cancer (GC) who underwent curative intent gastrectomy were retrospectively investigated. RGC resections with histological diagnosis of gastric adenocarcinoma were enrolled in the study. The risk score based on immune parameters was developed using binary logistic regression analysis. RGCs were divided into high-risk (HR), intermediate-risk (IR), and low-risk (LR) groups based on their immune score. The markers (CD3+, CD4+/CD8+ T cells and PD-L1) were selected for their potential prognostic, therapeutic value, and evaluated by immunohistochemistry (IHC). Results: A total of 42 patients with RGC were enrolled in the study. The score based on immune parameters exhibited an accuracy of 79% [the area under the receiver operating characteristic curve (AUC)=0.79, 95% confidence interval (95% CI), 0.63-0.94, P=0.002], and the population was divided into 3 prognostic groups: 10 (23.8%) patients were classified as LR, 15 (35.7%) as IR, and 17 (40.5%) as HR groups. There were no differences in clinicopathological and surgical characteristics between the three groups. In survival analysis, HR and IR groups had worse disease-free survival and overall survival rates compared to the LR group. In the multivariate analysis, lymph node metastasis and the immune score risk groups were independent factors related to worse survival. Conclusions: A scoring system with immune-related markers was able to distinguish prognostic groups of RGC associated with survival. Accordingly, tumor-infiltrating immune lymphocytes and PD-L1 status may serve as a potential prognostic biomarker for patients with RGC.