Forkhead-box A1 (FOXA1) expression in breast cancer and its prognostic significance.

The forkhead-box A1 (FOXA1) controls downstream transcription of oestrogen receptor (ER)-regulated genes. In this study, the biological and prognostic value of FOXA1 expression was assessed immunohistochemically in a large and well-characterised series of invasive breast carcinoma with a long term follow-up using tissue microarray. FOXA1 expression was associated with steroid hormone receptors (ERalpha, PgR and AR), other variables of good prognosis such as smaller tumour size, lower histological grade, luminal cytokeratins (CK18 and CK7/8), BRCA1 and E-cadherin. Its expression showed an inverse relation with basal CKs (CK14 and CK5/6) and P-cadherin. We found an association between high FOXA1 expression and a better survival in the whole series however; multivariate analysis showed that FOXA1 was not an independent prognostic marker. In conclusion, our results show that FOXA1 protein is associated with markers of good prognosis supporting its role as a growth repressor in breast cancer. In this series, FOXA1 was found not to be of an independent prognostic significance in breast cancer and as such its immunohistochemical assessment alone does not appear to have relevance in routine practice to stratify ER-positive (luminal-like) tumours into clinically significant subgroups.