compositions suitable for use as adjuvants in the preparation of vaccines , particularly those vaccines useful in the treatment of cancer , are provided . methods for inhibiting tumor growth in an animal are also disclosed . methods for immunizing an animal against cancer , such as prostate cancer , are also described . the adjuvants described are comprised of an extracellular matrix material , such as small intestinal submucosal tissue . the preparations may take the form of sheets , gels , liquids , trocar , or other solid or semi - solid preparation . the invention provides for enhanced tumor inhibition of 2 - fold or greater , compared to vaccine preparations without the extracellular matrix material , or from 4 - to 5 - fold , compared to preparations without the adjuvant promoting extracellular materials .