Breast Cancer Adaptation to Oxygen Stress: Mechanisms of Tumor Survival, Progression, and Therapeutic Resistance

Abstract

Breast cancer cells encounter heterogeneous oxygen conditions arising from abnormal vasculature, impaired perfusion, rapid proliferation, and fluctuating blood flow. Adaptation to oxygen stress is increasingly recognized as a major driver of tumor progression and therapeutic resistance. This review integrates current evidence on the mechanisms through which breast cancer cells adapt to oxygen stress and identifies opportunities for precision therapeutic intervention. Oxygen stress activates hypoxia-inducible factors and interconnected signaling networks that coordinate metabolic reprogramming, mitochondrial adaptation, reactive oxygen species generation, and redox homeostasis. These responses are reinforced by autophagy, unfolded protein response, epithelial–mesenchymal plasticity, cancer stemness, extracellular-matrix remodeling, angiogenesis, and immune suppression. Together, these mechanisms sustain cellular survival, facilitate invasion and metastasis, and promote resistance to chemotherapy, radiotherapy, endocrine therapy, HER2-directed treatment, and other targeted approaches. Oxygen-stress responses vary across breast cancer subtypes, emphasizing the need for biologically informed therapeutic strategies. Potential precision approaches include targeting hypoxia signaling, glycolytic and mitochondrial dependencies, lactate metabolism, antioxidant systems, autophagy, proteostasis, hypoxia-activated pathways, and hypoxia-associated immune suppression. Integrating molecular biomarkers, metabolic profiling, spatial technologies, and functional imaging may improve identification of tumors with actionable oxygen-stress dependencies. Oxygen-stress adaptation represents an interconnected survival network rather than a single hypoxia pathway. Therapeutically exploiting tumor-specific adaptive dependencies, while accounting for subtype and spatial heterogeneity, may provide new opportunities to overcome treatment resistance and improve precision management of breast cancer.