Moreover, TAM-SPP1, representing bone marrow-derived macrophages, is characterized by high expression of lipid-related genes like APOC1, APOE, and TREM2. Existing evidence suggests that SPP1+TAM and TREM2+TAM (also known as lipid-associated macrophages) are abundant in various types of cancers, such as colon cancer [108], lung cancer [63], and hepatocellular carcinoma [109, 110]. Here, APOE is linked to cancer.