Contemplated compositions and methods utilize a combination of a polyphenol and a non-polyphenol cyclooxygenase-2 inhibitor. Preferably, the compositions are pharmaceutical and/or nutraceutical compositions and formulated in a dosage form and amount such that the polyphenol and the non-polyphenol cyclooxygenase-2 inhibitor are effective to reduce tumor incidence and/or multiplicity. In preferred aspects, the polyphenol is epigallocatechin gallate, epigallocatechin, epicatechin gallate, epicatechin, and/or a mixture of polyphenols isolated from a plant (e.g., polyphenon E), and the cyclooxygenase-2 inhibitor is rofecoxib, celecoxib, and/or valdecoxib.