-- research for breast cancer (BC) biomarkers may lead to the discovery of novel therapeutic targets and predictive factors that will improve clinical outcome prediction. Forkhead box protein A1 (FOXA1) is pioneer factor serves both as a growth stimulant and a repressor and the significance role of this protein as a prognostic and therapeutic biomarkers still controversial, so the aim of this study was identify the precise role of FOXA1 protein expression in prediction of BC patients outcome, recurrence and treatment of BC by immunohistochemical (IHC) staning method. The current research was done during the period September 2021 and May 2022 at the University of Kufa's, Faculty of Medicine, Middle Euphrates Unit for Cancer Research. In this study, Seventy three tissues samples embedded in wax block taken from BC patients with (52.71+11.55) years who had surgery between 2014-2020 and thirty seven of normal (non tumoral) breast tissues samples with (54.17+10.84) years as a control group. These samples collected from archieves of the two private laboratories and re-evaluted by two pathologist. Positive nuclear IHC expression of FOXA1 is considerably reduced in 43 BC cases (58.9%) compared to 38 control individual (100%).

The Forkhead box (FOX) protein family includes FOXA1, and is a transcription factor (TF). It work as a pioneer factor, interacting with compressed chromatin to allow ER to bind more easily later (Nagaraj and Ma, 2021). It significantly contributed to the development and invasiveness of endocrine-resistant cells by changing the ER dependent transcriptome in numerous endocrine-resistant preclinical BC cell types (Chun et al., 2017). The present study is done during the period September 2021 and May 2022 at the University of Kufa's, Faculty of Medicine, Middle Euphrates Unit for Cancer Research.  as a control group. These samples gathered from archives of the two private laboratories and re-evaluted by two pathologist. Positive nuclear IHC expression of FOXA1 is significantly reduced in 43 BC cases (58.9%) compared to 38 control persons (100%) while negative nuclear IHC expression of FOXA1 is significantly reduced in BC patients, 30 cases (41.1%) compared to 0 control  persons (0.0%), Odd ratio 1.66, 95% CI (1.37-1.98), P=0.0001. Moreover, FOXA1 positivity was elevated significantly in patients with grade I and II (P=0.002) and absent of lymph node metastasis (p=0.027).