Abstract A critical step in the metastatic cascade is the survival of circulating tumor cells (CTCs) within the bloodstream. Although interactions between CTCs and various hematopoietic cells have been described. the role of red blood cells (RBCs) remains underexplored. This study investigated the interactions between tumor cells and RBCs from breast and lung cancer patients. https://www.roneverhart.com/Gul-Rune/