Abstract: The invention comprises the administration of an amount of honokiol (HNK) and Modified Citrus Pectin (MCP) or similar pectin or alginate in amounts synergistic to inhibit cancer. The inhibition can be of the formation of cancer, the progression of a cancer already formed, or the transformation of a primary cancer to a metastatic one. HNK and MCP appear to be synergistic across their effective ranges, and the synergy may be due in part to the binding of galectin-3 on the surface of tumor cells by MCP, which better presents the cell for the cytotoxic effects of HNK. Compositions of matter which combine the two agents, HNK and MCP, in synergistic amounts intended for daily administration are also contemplated. The administration of MCP and HNK may be combined with the administration of conventional anti-cancer therapeutics.