Experimental Studies on the Spread of Cancer in the Lymphatic System

Summary

Experiments were performed to discover whether tumor cells in the thoracic duct are all carried to the lungs or whether some of them may go directly to thoracic lymph nodes. V₂ carcinoma cells were injected in the thoracic duct of some rabbits and in a vein of others. In both series, tumors developed in the lungs. In animals receiving thoracic duct injections, tumors also developed in mediastinal and intercostal lymph nodes.

Lymphatic connections between the thoracic duct and lymph nodes were demonstrated by injecting dye into the duct. Some of these lymphatic channels are afferents, for tumor injection into the duct led to neoplastic growth in the subcapsular lymph sinuses of nodes, where afferent lymphatics empty. Only in a few instances was tumor found in the medulla or hilus, indicating retrograde passage through efferent branches. Thoracic duct branches were also demonstrated in a human fetus by dye injection. Mediastinal, intercostal, and left supraclavicular nodes were stained.

It is concluded that tumor cells may pass directly from the thoracic duct to nearby lymph nodes and there grow into secondary tumors without the necessity of passing through the lungs. Passage from the duct apparently occurs most frequently through afferent branches of the duct to the nodes. Virchow's node in man probably results from tumor cell emboli following a similar route to the supraclavicular nodes.