The complex landscape of luminal breast cancer.

The breast epithelium, vital for mammary gland function, is influenced by oestrogen through the oestrogen receptor (ER) signalling pathway. Luminal breast cancer (BC), characterised by ER expression, comprises the majority of all BCs and presents significant clinical challenges due to therapy resistance and recurrence. Despite advancements in understanding luminal disease, improving long-term survival and reducing relapse of BC patients by predicting therapy efficacy and understanding resistance mechanisms remain critical challenges. This review discusses luminal BC biology, focusing on the molecular classification of primary disease, metastatic spread, and experimental models.