The immune system plays an intricate role in tumorigenesis, therefore cancer immunotherapy borrows concepts both from autoimmunity and vaccinology. Due to tumor-induced immune suppression, the adjuvant setting seems most suitable for immunotherapy, which optimally targets multiple tumor associated antigens after removal of the bulk of the tumor. The responses elicited need not match the intensity of those against pathogens. Retrospective studies suggest that cancer patients' survival correlates with low-titer anti-tumor IgM antibodies. Carbohydrate mimetic peptides (CMPs) prove instrumental as immunogens by boosting similar persistent IgM anti-tumor responses, engaging the innate/adaptive immunity interface and promoting cytotoxic responses and epitope spreading.