As previously reported for advanced cancer patients, CD4posCD25hiFoxP3pos regulatory T cell (Treg) levels in our study participants were higher than those of healthy controls; however, the immunizations did not increase Treg and the magnitude of the CEA-specific T cell and antibody responses did not differ between peripheral blood Treg levels demonstrating that the VRP-CEA(6D) immunizations could break tolerance to CEA regardless of the immunosuppressive effects of Treg. This evidence concerns the gene CEACAM5 and cancer.