In addition to direct interaction with cancer cells, NETs can cause changes in the tumor microenvironment, activating the TLR4/9–COX2 axis to trigger tumor-induced inflammatory responses and induce the release of inflammatory cytokines, such as TNF-α, IL-6, IL-8 and CXCL-10, thus promoting tumor growth and tumor cell metastasis and invasion (Figure 6) [189,195,196]. The gene discussed is TLR4; the disease is cancer.