An experimental model for studying factors which influence metastasis of malignant tumors

Implantation of Lewis lung tumor into the leg muscle of BDF1 male mice resulted in tumor growth at the site of implantation. Metastasis to the lungs regularly occurred, early in the course of the disease, when the primary tumor was small and the mouse was capable of tolerating both surgery and chemotherapy. Treatment with cyclophosphamide alone was relatively ineffective in increasing the survival time of the animals and failed to increase the percentage of survivors. Radical surgery, performed early in the course of the disease, resulted in “cures” of almost 60% of the animals. Later, after definite metastasis had occurred, surgery alone was ineffective. Surgery plus adjuvant chemotherapy was in some instances more effective than surgery alone or chemotherapy alone in yielding “cures”. Also, in many instances, the combination constituted more effective treatment in increasing the survival time of the animals. However, cumulative drug toxicity appeared to interfere with the potential of the combination modality of therapy.