Recent Insights Into Breast Cancer: Molecular Pathways, Epigenetic Regulation, and Emerging Targeted Therapies

Breast cancer remains the most prevalent malignant tumor and a leading cause of cancer-related mortality among women worldwide. The disease comprises distinct molecular subtypes that influence tumor behavior, metastatic potential, and therapeutic response. This review presents recent advances in breast cancer research, with a particular emphasis on molecular and epigenetic mechanisms that contribute to tumor development, progression, and treatment resistance. Key signaling pathways-including estrogen receptor (ER), human epidermal growth factor receptor 2 (HER2), Notch, fibroblast growth factor receptor (FGFR), Wnt, and Hedgehog-play essential roles in the regulation of mammary stem cells and oncogenesis. Increasing evidence highlights the significance of epigenetic alterations such as DNA methylation, histone modifications, and microRNA expression in modulating gene activity relevant to tumor initiation and therapy resistance. Epigenetic molecular targets, including DNA methyltransferases (DNMTs), histone deacetylases (HDACs), EZH2, and non-coding RNAs, are gaining attention for their potential use in diagnosis, prognosis, and targeted therapy. Integration of multigene panel testing with epigenetic biomarkers has facilitated improved risk assessment and the development of individualized treatment strategies. Moreover, novel therapeutic approaches-such as CAR-T cell therapy, nanoparticle-mediated drug delivery systems, and the involvement of circular RNAs (circRNAs) in immune modulation-offer promising directions for precision medicine. This review consolidates current insights into the molecular and epigenetic landscape of breast cancer to provide a comprehensive understanding of disease complexity and to inform the development of more effective, personalized treatment options.