Prognostic relevance of specific TIL (CD4+, CD8+, and FOXP3 + T-cell infiltrates) in triple-negative breast cancer: short- and long-term outcomes

BACKGROUND: Breast cancer is a heterogeneous malignant disease that remains as one of the most prevalent cancers globally. Triple negative breast cancer (TNBC) accounts for 15% of the total of breast cancers and presents high tumor immunogenicity and a tumor microenvironment that plays a critical role in disease progression and patient outcomes. METHODS: This study evaluated a total of 30 tissue samples from female patients with TNBC, to characterize specific immune cells within the tumor tissue and investigate their relationship with short (pathological complete response, pCR), long (disease-free survival, DFS) and clinical outcomes. Tumor-infiltrating lymphocytes (TIL) were assessed by immunohistochemistry (IHC) on tissue microarrays (TMA), complemented by digital analysis for standardized quantification. RESULTS: Our results highlight the influence of CD4⁺ T cells on short-term outcomes: high CD4⁺ T-cell levels were significantly associated with achieving pCR. High CD8⁺ T-cell levels were also significantly associated with axillary lymph node negativity.Regarding long-term outcomes, higher CD4⁺, CD8⁺ and FOXP3⁺ T-cell levels showed a non-significant tendency toward improved DFS. CONCLUSIONS: These findings suggest that high levels of CD4 + T cells and CD8 + T cells are positive predictors of immediate, long-term prognosis and clinical prognosis in patients with TNBC. This study enhances the understanding on the immunological interests in specific subtypes of TIL and identifies potential biomarkers that could drive advancements in precision medicine for breast cancer management.