Role of the vertebral venous system in metastatic spread of cancer cells to the bone.

Bromodeoxyuridine (BrdU) labeled human prostatic cancer cells, PC-3, and murine osteosarcoma cells, POS-1 were injected into the tail veins of male mice under concomitant temporal occlusion of inferior vena cava. Five minutes after release of the venous occlusion, animals were sacrificed and various tissues, organs and the vertebral bones were examined immunohistochemically using an application of BrdU-anti-BrdU methods. Obvious BrdU labeled tumor cells, isolated or clumped, were demonstrated within the venous channels along the vertebral column, the epidural venous channels around spinal nervous tissues, in the bone marrow of lumbo-sacral vertebrae and intra- and peri-prostatic venous channels. The results suggest that a blockade of short duration of venous flow at the inferior vena cava can result in the bypassing of tumor cells through the vena cava to the vertebral venous system, which has a close connection with the peri-prostatic venous plexus. Thus, the vertebral venous system may play an important role in the metastasis of prostatic carcinoma to bone. In addition this experimental procedure is a very valuable model for studying mechanisms and prevention of bone metastases from prostatic carcinoma.