Changing metastatic patterns of a transplantable rat osteosarcoma.

Metastatic behavior patterns in 303 untreated Sprague-Dawley rats bearing a transplantable cerium-144-induced osteosarcoma is described. The influence of survival time, sex, age of donor and recipient animals at time of transplantation, on the development of metastasis in lungs, kidneys, lymph nodes and liver was investigated. Nearly all (98.7 per cent) rats bearing osteosarcomas in the knee region developed primary hematogeneous lung metastases and 10.6 per cent of these developed secondary metastasis in the kidneys. A further primary, lymphogenous metastatic spread occurred in 15.5 per cent of the animals. Ninety-two per cent of the rats died because of lung metastases, but animals with long survival times developed significantly more extrapulmonary metastases than animals with a shorter survival time. This is an agreement with the observed change in metastatic patterns in osteosarcoma patients with prolonged survival after adjuvant chemotherapy. Moreover, the age of the donor-tumors and the recipient animals influenced survival time and consequently metastatic patterns. It was therefore possible to keep available several groups of osteosarcoma-bearing animals with different expectations of survival time. The results of transplantation of the same tumor by the intraperitoneal and the intravenous route are also presented.