Differential infiltration of CD4+ and CD8+ T cells and expression of PD-L1 in paired biopsy and resection specimens of gastric and colorectal adenocarcinomas.

OBJECTIVE

To compare CD4+ T cell, CD8+ T cell infiltration and PD-L1 expression between paired biopsy and resection specimens in gastric and colorectal adenocarcinoma, and evaluate their clinical significance.

METHODS

Paired biopsy and resection specimens from 38 gastric and 40 colorectal adenocarcinoma patients were assessed by immunohistochemistry for CD4+ T cell, CD8+ T cell density and PD-L1 expression. Correlations with clinicopathological parameters and tumor markers were analyzed.

RESULTS

In gastric adenocarcinoma, resection specimens showed significantly higher CD4+ T cell, CD8+ T cell density and PD-L1 expression than biopsies (all P<0.05), with CD4+ T cells positively correlated with CA19-9 (R = 0.523, P = 0.026). In colorectal adenocarcinoma, CD8+ T cell density was higher in resection specimens (P = 0.0353); CD4+ T cells negatively correlated with Ki-67 (R=-0.370, P = 0.019), and CD4+/CD8+ ratio negatively correlated with mismatch repair protein expression (R=-0.342, P = 0.029). In both cancers, CD4+/CD8+ ratios at tumor center and invasive margin were positively correlated (gastric: R = 0.5683, P = 0.0002; colorectal: R = 0.7324, P<0.0001). Preoperative neutrophil-to-lymphocyte ratio positively correlated with tumor diameter in both cancers (gastric: R = 0.449, P = 0.011; colorectal: R = 0.631, P = 0.001). CD4+ T cell density differed significantly between cancer types (P <0.0001). ROC analysis demonstrated limited predictive value of biopsy specimens for surgical findings, particularly in colorectal cancer (AUC 0.5-0.7).

CONCLUSION

Biopsy specimens inadequately represent the immune microenvironment of resection specimens, especially in gastric adenocarcinoma. Tumor-type-specific immune assessment of biopsies is essential for guiding precise immunotherapy decisions.