The estrogen/ER ratio affects the efficacy of immunotherapy.[179] A study on breast and colorectal cancer demonstrated that the overexpression of ERβ has a synergistic effect with anti‐PD1 therapy.[180] The administration of an ERβ agonist increased the infiltration of CD8+ T cells while attenuating the levels of CSF1 from tumors, subsequently reducing the population of CSF1R+ myeloid‐derived suppressor cells and enhancing the effectiveness of anti‐PD1 therapy. This evidence concerns the gene CSF1 and colorectal cancer.