The lymphnodal clonogenicity and kinetics of metastatic cells disseminated by a transplanted rat carcinoma.

We report data on the transplantation of primary tumour cells and of lymph nodes containing metastatic cells disseminated by a mammary carcinoma (LMC1) implanted s.c. in the Johns' Strain Wistar rat. A new method is described for deriving the TD50 of metastatic cells and for comparing their lymphnodal clonogenicity in the transplanted and the original, i.e. 'primary' tumour host. The TD50 for transplanted primary LMC1 cells was approximately 12 (fiducial limits 8-20 cells), and the latency of the 8-10mm tumours formed (T8-10) after inocula of 10(2) to 10(5) cells decreased linearly with the logarithmic increase in the number of cells injected. From the T8-10 and tumour incidence data for transplanted inguinal, axillary and para-aortic nodes, the TD50 for metastatic cells was calculated to be 1120 cells (fiducial limits 790-1603 cells) indicating that the clonogenicity of naturally disseminated metastatic cells was about a 100 fold lower than that determined for transplanted primary tumour cells. The incidence and T8-10 data for axillary, inguinal and para-aortic lymph node metastases in primary-tumour-excised hosts suggests that, although metastatic cells may continue translymphnodal dissemination in situ, their TD50 is still consistent with that determined by node transplantation.