observed that although MCF-7 cells can induce TNF-α-treated macrophages (conditioned macrophages) to produce IL-6, IL-8, CCL5, TNF-α, and other inflammatory cytokines in the absence of E2 or in the presence of an ERα antagonist, endocrine resistance in breast cancer cells is promoted in a non-hormone-dependent manner via the TNF-α/IL-6 pathway (142). This evidence concerns the gene ESR1 and breast cancer.