Host's immune state and kinetics of local tumor growth control--progression of postoperative lung metastasis.

In a study of the progression of lung metastases in tumor-bearing and tumor-excised mice as a function of the host's immune status and of the rate of local 3LL tumor development, the following observations were noted. 1) The total metastatic volume was larger in mice transplanted intrafootpad with the lower doses of 3LL tumor cells (1 x 10(5)--3 x 10(4)) than in mice inoculated with high doses of tumor cells (5 x 10(-6)--1 x 10(6)). 2) A dramatic acceleration of metastatic development followed surgical removal of the local tumor which developed following inoculation of low, but not high doses of 3LL tumor cells. 3) In immunoimpaired mice, growth of the local tumor induced by inoculation of 3 x 10(6) or 1 x 10(5) 3LL tumor cells was enhanced in cyclophosphamide-treated (200 mg/kg) mice and retarded in B mice, yet metastasis development was accelerated in both types of immunosuppressed tumor-bearing mice. Tumor excision was an additional stimulus for metastatic growth. In immunosuppressed animals, the growth of postoperative pulmonary metastases accelerated to the same degree, independent of whether local tumors had been produced by high or by low doses of 3LL tumor cells.