The effective epitope of CA215, a known cancer marker and antigen, has been demonstrated to include a carbohydrate moiety of defined composition and to be non-reactive with anti-human IgG, IgA and IgM, although CA215 is an immunoglobulin heavy chain-like molecule. The defined epitope may be used to prepare immunogenic compositions for treatment and prevention of cancers in humans and may be optimized as to protocol and formulation in animal model systems. Improved protocols for diagnosis and treatment are also described.
