Influence of surgery, irradiation, chemotherapy, and immunotherapy on growth of a metastasizing rat mammary adenocarcinoma.

Based upon the hypothesis that a factor most pertinent to the absence of an effective immune response in cancer is the inadequacy of the antigenic stimulus provided by the neoplasm, either in terms of weak immunogenicity of the tumor antigen or of the necessary antigen mass available to the reticuloendothelial tissues at any one time for effective sensitization, the host immune response capabilities were stimulated within a time frame synchronous with a greater release of tumor antigens. In the treatment of a metastasizing, solid tumor model syngeneic with F344 rats, immunotherapy was most effectively applied in combinations with chemotherapy and/or localized radiotherapy, therapeutic modalities that induced a degree of oncolysis and tumor resorption. Surgery combined with chemotherapy permitted evaluation of therapeutic effects against metastases. The methanol-soluble fraction of Mycobacterium butyricum was used as the nonspecific immunologic adjuvant.