It is known that the accumulation of MDSCs and Treg cells in colorectal cancer liver metastases is TNFR2-dependent in females; estrogen, by reversing extracellular vesicle-mediated immunity, leads to a significant decrease in the PD-L1+M2-like macrophage, Treg cell, and MDSC populations, and an increase in the cytotoxic CD8+ T cell population increased, thereby suppressing the tumor microenvironment inhibiting the growth of mouse colon cancer; the present study investigates the role of estrogen signaling within the microenvironment of rectal cancer. This evidence concerns the gene CD8A and rectal cancer.