Host resistance against tumor and its synergic effect with cancer chemotherapy.

The treatment of animals with non-neoplastic or neoplastic tissue before or after tumor transplantation inhibited the growth of transplanted tumor cells. This phenomenon was most clearly demonstrated when a sub-effective dose of chemotherapeutic agent was administered. In animals bearing a spontaneous tumor, the growth of auto-transplanted tumor was inhibited as compared with that of the same tumor transplanted in isologous animals. These findings suggested that the acquired resistance of the host against tumor inhibits the growth of a newly transplanted tumor.