Tumor-Infiltrating CD8 + Lymphocytes Predict Clinical Outcome in Breast Cancer

Breast carcinomas are often infiltrated by inflammatory cells, particularly macrophages and T lymphocytes, but the significance of these cells remains unclear. One possible role of these inflammatory cells is that they represent a cell-mediated immune response against the carcinoma. CD8(+) lymphocytes are a known crucial component of cell-mediated immunity. The purpose of this study was to explore the prognostic value of tumor-infiltrating CD8(+) cytotoxic lymphocytes in breast cancer. Tumor-infiltrating CD8(+) lymphocytes were assessed by immunohistochemical staining of tissue microarray cores from 1,334 unselected breast tumors from patients with long-term follow-up. The number of CD8(+) T cells was counted…