Experimental studies on the spread of cancer in the lymphatic system. IV. Retrograde spread.

This report is one in a series dealing with experiments designed to study the mechanics of the spread of cancer through the lymphatic system. In these experiments, viable transplantable tumor cells are injected directly into afferent lymphatics. Past work concerned the forward spread of cancer, from node to node and through the thoracic duct (~-4). Studies of lymphatic spread would be incomplete without consideration of retrograde spread, a form of metastasis occasionally seen in human cases (1). That is, cancer metastasizes not only from node to node as the lymph flows, but also to retrograde nodes, as well, in a direction counter to normal lymph flow. What pathways are used by tumor cell emboli while passing retrograde? YVhere do tumor cells first lodge in the retrograde node? Experiments were done to determine whether the retrograde spread of cancer in the lymphatic system could be reproduced experimentally as it is seen in man. If so, then the above questions may be answered.