The present invention provides for methods for immunizing actively against autologous carcinoembryonic antigen (CEA). The method encompasses that the immune system is engaged with variant CEA which is either administered as a protein vaccine, or is effected expressed by nucleic acid vaccination or live-viral vaccination. Preferred embodiments include immunization with variants that include at least one foreign T-helper epitope introduced in the CEA sequence. Also disclosed is variant proteins, DNA, vectors, and host cells useful for practising the method of the invention.