Nonorganophilic, hematogenous dissemination in the presence of positive lymph nodes of a malignant tumor in rabbits

Abstract

An animal model has been devised which for the first time allows direct investigation of the roles of vascular dynamics, hematogenous versus lymphatic pathways, and involved regional lymph nodes in malignant dissemination. The VX2 anaplastic carcinoma growing in the hindlimb of rabbits normally metastasizes exclusively to the lungs, yet in this study was made to metastasize exclusively to the liver by construction of a cavoportal shunt prior to tumor transplantation. This technique also provided separation of the tumor's venous and lymphatic outflow. Normal and shunted animals with forelimb transplantation of the tumor, which acted as controls for the effects of the shunt operation itself, showed the same metastatic pattern as normal rabbits bearing hindlimb tumors. These results are direct evidence that a primary tumor metastasizes according to non-organophilic circulation dynamics and that lymphatic pathways, including metastatic regional lymph nodes, have no role in distant metastasis.