Free tumor cell growth in the peritoneal cavity (ascites tumor) of mice bearing subcutaneous tumors.

Abstract

Summary 1.Mice bearing subcutaneous tumors on their backs and new mice (controls) were given intraperitoneal inoculations of a tumor of the same or of a different strain. After requisite time intervals, counts of tumor cells were carried out on specimens of peritoneal exudate from both groups. 2.In mice with a 2-day interval between two inoculations of S-37 or S-180 (fast-growing tumors), the peritoneal cell counts were about the same as in the controls, but with an interval of 4–7 days the counts were considerably higher than those in the controls. However, further increase of the tumor age was associated with an excess of free tumor cells in the exudate of control mice over that of experimental mice. 3.The increase in peritoneal tumor cell counts was eventually reversed by the removal of the tumor, but their decrease in mice with advanced subcutaneous tumors was not influenced by this procedure. 4.The data on the weight of subcutaneous tumors in animals with intraperitoneal growth did not show any significant variations from the controls. 5.It is presumed, in the light of earlier work by Greene and Barrett, that early subcutaneous growth induced systemic changes in the host favorable to secondary peritoneal growth and reversible by primary tumor removal. Advanced tumor growth induced a cachetic condition in the host, thus decreasing both the resistance of the host to malignant invasion and the viability of tumor cells. The balance of the two effects was unfavorable to the latter, under the conditions of out experiments.