The present invention provides a method of determining the success of a cancer therapy in an individual, comprising the step of measuring the frequency of occurence of an oncofetal antigen-specific subclasses in the individual's peripheral blood. Also provided is a method of determining whether protective immunity against a tumor will develop in an individual, comprising the step of measuring the frequency of oncofetal antigen-specific T cells, tumor cells and macrophages at the site of the tumor which secrete IL-10. Additionally, a method of determining whether an individual having a tumor will go into remission or remain in remission, comprising the step of measuring the frequency of oncofetal antigen-specific Th1 cells, Tc cells and Ts cells, IL-10 and interferon-.gamma. secreting T cells in the peripheral blood.