This study aimed to investigate the expression profile of FOXC1 in molecular sub­types of invasive breast cancer. Additionally, it sought to explore the association between FOXC1 expression and clinicopathological prognostic parameters to eval­uate its potential diagnostic and therapeutic implications.

A total of 122 invasive breast carcinoma cases from excision specimens were an­alysed. Immunohistochemical staining for FOXC1 was performed, with nuclear expression > 1% considered positive. The correlation between FOXC1 expression, molecular subtypes, and prognostic parameters was examined.

A significant negative correlation was found between FOXC1 expression and ER, PR, and HER2 in 122 cases, while FOXC1 expression was notably higher in the triple-negative breast cancer (TNBC) subtype. Additionally, FOXC1 expression showed a significant positive correlation with nuclear grade, histological grade, Ki67 index, and prognostic stage.

FOXC1 expression was found to be higher in TNBCs compared to other molecular subtypes, and FOXC1 expression was negatively correlated with hormone recep­tors and HER2. On the other hand, FOXC1 was significantly associated with high proliferation index, high-grade tumour, and prognostic stage. These findings sug­gest that high FOXC1 expression may indicate aggressive behaviour and may be a predictive marker for poor prognosis.