Iron Metabolism in the Colorectal Tumor Microenvironment: From Preneoplastic Lesions to Cancer Progression.

Colorectal cancer (CRC) is a major global health burden characterized by progressive genetic and metabolic alterations, with iron metabolism being increasingly recognized as a key contributor to tumorigenesis. This review provides an integrated synthesis of current evidence on iron metabolism across the continuum of colorectal cancer development, from preneoplastic lesions to advanced disease. We analyzed data from epidemiological, experimental, and mechanistic studies addressing systemic and cellular iron homeostasis, including the hepcidin-ferroportin axis, as well as iron handling within tumor cells and the tumor microenvironment. Available data indicate that colorectal epithelial cells progressively develop an iron-retentive phenotype, characterized by increased iron uptake and reduced export, leading to expansion of the intracellular labile iron pool. This imbalance contributes to oxidative stress, DNA damage, metabolic adaptation, and activation of oncogenic signaling pathways while also influencing immune responses. However, epidemiological findings on dietary iron and CRC risk remain inconsistent, highlighting the context-dependent nature of iron-related effects. In conclusion, iron metabolism represents a dynamic regulator of CRC progression and a mechanistic framework for understanding stage-specific tumor evolution, although further studies are needed to clarify how iron-dependent pathways differ across colorectal tumor subtypes and microenvironmental contexts.