Infiltration of CD8+ lymphocytes is an independent prognostic factor of biochemical failure-free survival in prostate cancer

Backgrounds: The adaptive immune system can potentially have dual roles in cancer development and progression by contributing to or suppressing tumor progression and metastasis. The aim of this study was to evaluate the prognostic impact of adaptive immune cells residing in different tumor compartments in prostate cancer.

Methods: Tissue microarrays from 535 patients were constructed from viable and representative tumor epithelial and stromal areas of primary PC tumors, as well as from normal epithelial and stromal areas. Immunohistochemistry was used to evaluate the density of CD3+, CD4+, CD8+, and CD20+ lymphocytes in both tumor epithelial and tumor stromal areas.

Results: In univariate analysis, a high density of CD3+ (P = 0.037) and CD8+ lymphocytes (P = 0.010) in tumor epithelial areas was associated with significantly shorter biochemical failure-free survival. When analyzing both tumor epithelial and stromal tissue compartments as one entity, similar relationships were observed for CD3+ (P = 0.046), CD4+ (P = 0.026), and CD8+ (P = 0.003) lymphocytes. In multivariate analysis, high densities of CD8+ lymphocytes limited to tumor epithelial areas (HR = 1.45, P = 0.032), as well as in the total tumor tissue (HR = 1.57, P = 0.007), were independent negative prognostic factors for biochemical failure-free survival.

Conclusions: A high density of CD8+ lymphocytes, especially in tumor epithelial areas, is an independent negative prognostic factor for biochemical failure-free survival.