In the tumor microenvironment, YKL-40 is primarily secreted by tumor-associated macrophages, lymphocytes, and tumor cells (20, 31–33) and is involved in extracellular matrix remodeling, neo-angiogenesis, and immune microenvironment modulation towards an inhibited anti-tumor response (20, 31–33). This evidence concerns the gene CHI3L1 and neoplasm.