Enterolobium cyclocarpum (EC) is an edible plant and a gum source for food industries. Its sulfated polysaccharide extract (SEC) was examined for cancer chemopreventive properties to estimate its anti-tumor activity. The modulation of carcinogen metabolism and the antioxidant activity revealed that SEC is a potent tumor anti-initiator since it inhibited cytochrome P450-1A (CYP1A) and induced carcinogen detoxification enzyme glutathione-S-transferase. SEC is also a weak scavenger for hydroxyl and peroxyl radicals. SEC was found to modulate macrophage functions into an anti-inflammatory pattern, where it enhanced macrophage proliferation and phagocytosis of fluorescein isothiocyanate-lipopolysaccharide (FITC-LPS). In addition, SEC strongly inhibited the nitric oxide (NO) generation in LPS-stimulated macrophages and induced the binding affinity of FITC-LPS to macrophages. SEC exhibited specific cytotoxicity against human hepatocellular Hep G2 carcinoma cells. SEC disturbed the cell cycle phase, as indicated by the concomitant arrest in S- and G2/M-phases that was associated with necrosis induction. A short-term initiation model for liver cancer was prepared using diethylnitrosamine (DEN) in rats. SEC inhibited the DEN-histopathological findings and reduced both CYP1A and the tumor initiation marker placental glutathione S-transferase (GSTP). Taken together, SEC could be used as an alternative gum in health food industries to provide cancer prevention in high-risk populations.