Association Between FOXP3/CD8 Lymphocyte Ratios and Tumor Infiltrating Lymphocyte Levels in Different Breast Cancer Subtypes.

Background/Aim: Patients with non-luminal breast cancer subtypes with high levels of tumor infiltrating lymphocytes (TILs) have better prognosis than those with luminal subtype. We evaluated the role of TILs according to the subtype. Materials and Methods: An immunohistochemical analysis of 139 breast cancer cases was conducted to calculate the FOXP3+/CD8+ T cell ratios and their relationships with TILs and disease-free survival (DFS) were evaluated. Results: FOXP3+/CD8+ T cell ratios were significantly associated with TIL levels only in luminal breast cancers (p=0.0001). Low FOXP3+/CD8+ T cell ratio was significantly associated with longer DFS (p=0.017). All luminal subtype patients with high TIL levels had high FOXP3+/CD8+ T cell ratios compared to only half of non-luminal subtype patients with high TIL levels. Conclusion: High FOXP3+/CD8+ T cell ratios in breast cancers may partly explain the worse prognosis of luminal breast cancers, but not that of non-luminal breast cancers with high TIL levels.