The development of spontaneous metastases after the removal of a “primary” tumor<i>II. Standardization protocol of 5 animal tumors</i>

Abstract

of growth and the size of a T primary turnor may be responsible for the number of metastases it produces.7,22-24 Some investigators, however, have suggested that a primary tumor may inhibit development of its metastases.l3.16r19 T h e authors have already stressed the necessity of standardizing a tumor-host system before attempting to draw conclusions from the experimental findi n g ~. ~~ This report will describe studies carried out with 5 transplantable tumor-host systems, demonstrating the comparative relationship of the presence of a primary tumor, or its removal, on the number and size of its metastases. MATE:RIALS AND METHODST h e systems studied were: (1) melanoma S91 Cloudman (carried in the thigh muscle of CDBA/2Fl mice; (2) amelanotic melanoma SSIA in DBA/p mice; (3) osteogenic sarcoma 112 in C3HfB/HeN mice; (4) sarcoma T241 Lewis in C57BIL/GJN mice; and (5) sarcoma clba49 in DBA/p mice.A 1 to 10 dilution of each tumor was prepared by passing 1 gm. of grossly viable tumor and 10 cc. of normal saline through a h e l l cytosieve.20All animals were G weeks old when tumor inoculum was injected into the hind leg of mice from the same strain as that in which the tumclr had been carried.Mice were housed individually.This increased the survival time of tumor-bearing control mice, thus permitting evaluation of the metastatic process over an additional period of time, and greatly increased the reproducibility of the responses.When the primary tumors were between 1.5