From Radical to Tailored Lymphadenectomy: The Role of Fluorescence Lymph Node Mapping in the Century-Long Debate on the Extent of Nodal Dissection for Colorectal Cancer

The optimal extent of lymphadenectomy for colorectal cancer has been debated for over a century. Ultraradical operations did not improve survival, and three regional approaches later defined surgical quality in different ways: station-based D3 dissection in Japan, the number of examined nodes in the United States, and complete mesocolic excision with central vascular ligation in Europe. Recent studies suggest that any benefit of extended central dissection may be confined to a minority of patients. Yet the extent of dissection is still decided on the basis of vascular landmarks, without seeing the lymphatic drainage of the individual tumor. This narrative review places fluorescence lymph node mapping (FLNM) with indocyanine green (ICG) within this debate. Because colonic lymph drains through a web-like network with skip metastasis, the sentinel node concept of breast cancer is not directly applicable. We propose that FLNM should map the D3 territory and drainage pathway of the individual tumor, show where central dissection may be extended, and check for residual fluorescent nodes, without reducing dissection below the extent we propose for the clinical stage. ICG is a drainage map rather than a metastasis marker, and tumor-replaced nodes may not fluoresce. We also review ongoing trials and emerging technologies.