FOXP3 expression and nodal metastasis of breast cancer.

Purpose: T regulatory cells, a subset of T lymphocytes, function to suppress immune responses. FOXP3, a member of the forkhead family of transcription factors, is a good marker for T regulatory cells. Since sentinel nodes are important sites of immunomodulation in breast cancer, we studied the association between T regulatory cells and nodal metastasis using FOXP3 expression in sentinel nodes with and without metastatic breast carcinoma.
Methods: Following sample size calculations, we selected 140 sentinel nodes from breast cancer patients; 70 with metastasis (sentinel node+) and 70 without metastasis (sentinel node-). FOXP3 expression in sentinel nodes was studied by immunohistochemistry. Cortical cells expressing FOXP3 were counted in 10 high power fields.
Results: In the evaluable cases, the node positive (n = 66) and negative (n = 69) groups were well balanced for all clinicopathological parameters except histological type. The mean number of T regulatory cells expressing FOXP3 (per 10 hpf) was 139 in the node positive and 132 in the node negative group (P = 0.540). The mean number of T regulatory cells was 162 in patients ≤35 years of age (n = 8) compared to 133 in older patients (P = 0.250). Primary tumor pathological characteristics like tumor type, grade, size, and ER, PR, and HER2 status did not correlate with FOXP3 expression.
Conclusions: The number of FOXP3-expressing T regulatory cells does not differ significantly between sentinel node+ and sentinel node- samples. It was also not affected by primary tumor characteristics like tumor type, grade, size, hormone receptor, and HER2 status.