Tumor Hypoxia

Tumor hypoxia is a state of genuinely low oxygen tension within tumor tissue, typically arising when rapidly proliferating cancer cells outgrow their blood supply or when tumor vasculature is structurally abnormal or damaged. Hypoxia activates hypoxia-inducible factors (HIFs), which reprogram cell metabolism and signaling to promote angiogenesis, immune evasion, and — in many cancers — invasion and metastasis. Because hypoxia can also arise indirectly (for example, through constitutive HIF activation independent of true low oxygen, as in pseudohypoxia), directly visualizing or measuring oxygen tension is often necessary to confirm genuine tissue hypoxia rather than infer it from HIF pathway activity alone.