Effect of Intravenously Injected Radioisotopes on Metastatic Tumor Cells in Organs of the Mouse. ∗

Abstract

Summary and Conclusion

1. Intraperitoneal inoculation of liver brei from sarcoma-37 (i.p. growth, 5-day-old) induced tumor growth in nearly all of mice. This was attributed to the presence in the liver of metastatic cells spread from the primary tumor. Similar results were obtained only in rare instances with liver brei from the mice of the same series injected intravenously with colloidal Au¹⁹⁸ on the date of primary tumor inoculation (graft) or 2 days earlier or later. Analogous difference in results was recorded in experiments with i.p. inoculation of lung brei from tumor-bearing mice untreated and treated intravenously with radioactive chromic phosphate. It was concluded that injected radioisotopes reduced the number and the viability of metastatic tumor cells in the liver or in the lung. 2. Tumor growth from the organs which retain only small amounts of particulate isotopes (spleen) or none was but slightly inhibited or not at all. It was concluded that retention of radioisotopes by the organ was a prerequisite for their effect on metastatic tumor cells in this organ. 3. The possibility to induce damage to metastatic tumor cells without inflicting similar damage to normal tissues of the host was attributed to high vulnerability of metastatic cells as free cells (i.e. before their organized growth). 4. It is suggested that the method reported above may be useful for screening the activity of radioactive and chemical agents against metastatic tumor cells in organs of the mouse, and it is presumed that in certain clinical conditions it may be attempted to attack selectively metastatic tumor cells by suitable radioisotopes.