The ongoing development of monoclonal antibody technology may eventually lead to the selective targeting of human carcinoma lesions of MoAbs conjugated with a variety of cytotoxic agents (i.e. radionuclides, drugs, etc.). The antigen phenotype of the carcinoma cell will play an important role in the efficacy of the MoAbs. Clearly, the human tumor antigens that are expressed on all carcinoma cells and with a high antigen density should provide the optimal target for the MoAbs. More often, however, the human tumor antigens whose expression is highly selective for human tumor cells will also exhibit a certain degree of heterogeneity. Therefore, the ability of a cytokine, such as interferon or 8-Cl-cAMP, to augment the level of expression of human tumor antigens such as TAG-72 and CEA, may play an important role in an adjuvant setting for immunoscintigraphy and/or immunotherapy. Further research will focus on experimental model system as well as clinical trials to determine whether human recombinant interferon administered with an anti-carcinoma MoAb will be an effective combination to enhance tumor detection and/or therapy. It is conceivable that in subsequent years effective approaches of treating malignancies may include a new combination of biological/immunological therapy based on the biology of the tumor cell population.