Gastrointestinal Cancer and the Lymphatic System: Patterns of Micrometastasis and Lymphatic Mapping with Clinical Outcome

摘要

Precise evaluation of lymph node status is the most important factor for determining clinical outcome in treating gastrointestinal (GI) cancer. Unfortunately, lymph node metastasis (MA) may not always be accurately assessed through a preoperative work-up. Because lymphatic drainage of the GI tract is much more complicated than other anatomical sites, skip MA occurs rather frequently. Currently, sentinel lymph node (SLN) mapping has become highly feasible and accurate for staging GI cancer, and has clearly developed into a new therapeutic modality. The diagnosis of nodal MA, including micrometastasis (MM) using immunohistochemical and molecular technology, has been nearly achieved through GI cancer surgery. Furthermore, the sixth edition of the tumor node metastasis (TNM) classification has recently been redefined as "sentinel nodes (SN)," "micrometastasis (MM; 0.2-2 mm in diameter)," and "isolated tumor cells" (ITC; <0.2mm). The clinical significance of MM or ITC in SNs may differ among various organs. In particular, the prognostic value of MM detected by molecular technology remains controversial. The purpose of this symposium was to focus on the present status of SN navigation surgery in the three major types of GI cancers (esophagus, stomach, and colon), as well as to discuss the clinical significance of SLN biopsy, including the prognostic value of lymph node MA and MM identified in SN. The clinical impact of circulating tumor cells (CTCs) or bone marrow aspirates was also discussed. All speakers showed favorable results for identifying the GI SLN. Thus, accurate detection and diagnosis of lymph node MA including MM in SLNs has achieved a selection of more sophisticated, tailor-made approaches in clinical practice.