FOXP3 expression is related to high Ki-67 index and poor prognosis in lymph node-positive breast cancer patients.

BACKGROUND

Recent preclinical studies have shown that Forkhead box protein 3 (FOXP3) is an important tumor suppressor gene. The clinical and prognostic implication of FOXP3 expression in breast cancer cells still remains controversial.

METHODS

We evaluated the FOXP3 expression status of 183 patients who underwent curative surgery for breast cancer using the immunohistochemical assay of tissue microarray.

RESULTS

We found FOXP3 expression in 51 out of 183 (27.9%) surgically resected breast cancer tumors, and 33 patients were scored as weak positive and 18 as strong positive. FOXP3-positive tumors were associated with significantly higher nuclear grade, higher histologic grade and a more negative estrogen receptor status. The FOXP3 expression level was independently associated with high Ki-67 index in a logistic regression model. In the node-positive subgroup, strong FOXP3 positivity was related to poor disease-free survival and disease-specific survival compared to FOXP3-negative patients, whereas there was no survival difference between FOXP3-negative and FOXP3-weak-positive patients. Multivariate analysis with adjustment for patient age and human epidermal growth factor receptor 2 status demonstrated significantly poor survival of FOXP3-strong-positive patients in node-positive patients.

CONCLUSION

Our results suggest that strong FOXP3 expression in breast cancer cells is associated with poor prognosis and high Ki-67 index.