To detect the expression level of forxhead box Protein 3 (FoxP3) and CD8 in invasive ductal carcinoma of breast Lumina B, investigate the relevance between FoxP3⁺ regulatory T lymphocyte (Treg) and CD8⁺ cytotoxic T lymphocyte (CTL) as well as prognosis of breast cancer patients.

Immunohistochemistry was used to detect the expression level of FoxP3 and CD8 in the paraffin-embedded breast cancer samples. One-sample t test was applied to analyze the relationship among the expression levels of FoxP3 and CD8 of patient’s age, tumor size, nodal status, and histophathologic grade. Kaplan meier Log-rank was used to analyze the correlation between the expression level of CD8 and FoxP3 and the overall survival and disease-free survival of breast cancer patients.

The expression of CD8 is associated with tumor diameter ≤2 cm, lymph node negative metastasis, and with lower histopathologic grade (gradeⅠ/Ⅱ) (P<0.05). The level of FoxP3 is significantly related to tumor diameter >2 cm, lymph node metastasis (P<0.01). High expression level of FoxP3 infiltrating in tumor was could reduce the desease-free survival of breast cancer patients (P<0.05), while low expression of CD8 prolonged desease-free survival (P<0.01).

Tumor-infiltrating CD8⁺ CTLs are associated with good prognosis, whereas tumor-infiltrating FoxP3⁺ Tregs are associated with adverse outcomes.

Invasive ductal carcinoma of breast; Tumor-infiltrating T lymphocyte; Regulatory T lymphocyte; Cytotoxic T lymphocytes; Forxhead box protein 3; CD8