The growth characteristics of metastases from experimental renal tumors.

Wistar-Furth rats and BALB/c mice were implanted with tumor cells from metastases or primaries of an experimental Wilms' tumor or an experimental renal cell adenocarcinoma. The survival time, metastasis formation and growth of the primary tumor after implantation of metastatic tumor cells did not exceed those found after implantation of tumor cells from the tumor primaries. It is concluded that the higher growth rate usually found in metastases is not necessarily due to a selection of metastatic cells with a short cell growth cycle but that there are other environmental factors enhancing the growth of metastases.