Bonghan Ducts as Possible Pathways for Cancer Metastasis

Objective: The present study has been designed to find a possible new route for the metastasis of cancer cells on the fascia surrounding tumor tissue using a novel technique of trypan blue staining. Materials and Methods: Tumor tissues were grown in the skin of nude mice after subcutaneous inoculation with human lung cancer cells. Trypan blue was recently identified as a dye with specificity for Bonghan ducts (BHDs) and not other tissues, such as blood or lymph vessels or nerves. Results: We demonstrate that the trypan blue staining technique allows the first visualization of BHDs which are connected to tumor tissues. Conclusion: Since BHDs are known to make up a circulatory system corresponding to acu puncture meridians or collaterals, we propose that, in addition to the currently known blood or lymph vessels, BHDs on tumor tissue fascia may be a novel pathway for metastasis.