Mechanisms of Metastasis in Colorectal Cancer and Metastatic Organotropism: Hematogenous versus Peritoneal Spread

Figure 4

Mechanisms of metastasis in CRC—hematogenous versus peritoneal spread. Hematogenous spread: Tumor cells undergo EMT and leave the primary tumor. Through angiogenesis tumor cells find entrance into the circulatory system. During transport CTCs are protected by platelets and neutrophils from immune attacks and shear stress. Using distinct adhesion molecules CTCs then attach to the liver stroma and form colonies. Peritoneal spread: Tumor cells leave the primary tumor through spontaneous tumor cells shedding, surgical interventions, or exfoliation into the lymphatic system. In the peritoneal fluid, tumor cells form clusters to evade anoikis. Using certain adhesion molecules tumor cells attach to the peritoneum and use angiogenesis to further spread in the peritoneum. Factors that have been identified to play a role in specific parts of this multistep process in CRC are highlighted grey.