At the first stage of the tumor development activity of M1 macrophages, in particular, increased levels of ROS, NO, and the active inflammation process help them to destroy tumor cells, But as the tumor progresses and produces recruiting and polarization factors, such as IL-34, colony stimulating factor 1 (CSF1), M2-like macrophages start to predominate in the TME, which prohibit anticancer response and promote tumor growth and progression, contributing to proliferation and migration of cancer cells, angiogenesis, and metastasis (see Section 3 of this review). The gene discussed is IL34; the disease is neoplasm.