The epithelium-stroma interface serves as a barrier to immune cell infiltration across tumor immune phenotypes in epithelial cancers

Tumor immune phenotypes—immune-infiltrated, immune-desert, and immune-excluded—are characterized by the presence and spatial distribution of lymphocytes within the tumor bed and are associated with patient response to immune checkpoint inhibitor therapy.

Understanding how lymphocyte density is distributed at the cancer epithelium–stroma boundary can deepen our understanding of immune phenotypes and provide insight into how barriers to lymphocyte entry into the cancer epithelium may influence response to immunotherapy.