PTGS2 and Obesity: Importantly, such a cascaded immunological effect of Lipo/CXB@Hydrogel treatment amplifies CTL proliferation and activity specifically through targeting the arachidonic acid (AA)/COX-2/PGE2 signaling axis, a central hub linking lipid metabolism and inflammation, initiating a long-lasting immune response to suppress colorectal tumor postsurgical recurrence and metastasis in obesity contexts.