The gastrointestinal tumor microenvironment.

Over the past decade, the microenvironment of gastrointestinal tumors has gained increasing attention because it is required for tumor initiation, progression, and metastasis. The tumor microenvironment has many components and has been recognized as one of the major hallmarks of epithelial cancers. Although therapeutic strategies for gastrointestinal cancer have previously focused on the epithelial cell compartment, there is increasing interest in reagents that alter the microenvironment, based on reported interactions among gastrointestinal epithelial, stromal, and immune cells during gastrointestinal carcinogenesis. We review the different cellular components of the gastrointestinal tumor microenvironment and their functions in carcinogenesis and discuss how improving our understanding of the complex stromal network could lead to new therapeutic strategies.