Compositions suitable for use as adjuvants in the preparation of vaccines, particularlythose vaccines useful in the treatment of cancer, are provided. Methods for inhibitingtumor growth in an animal are also disclosed. Methods for immunizing an animalagainst cancer, such as prostate cancer, are also described. The adjuvants describedare comprised of an extracellular matrix material, such as small intestinalsubmucosal (SIS) tissue. The preparations may take the form of sheets, gels,liquids (injectable), trocar, or other solid or semi-solid preparation. Theinvention provides for enhanced tumor inhibition of 2-fold or greater, comparedto vaccine preparations without the extracellular matrix material, or from4- to 5-fold, compared to preparations without the adjuvant promoting extracellularmaterials.
