Current status and future prospects of sentinel node navigational surgery for gastrointestinal cancers

Until the late 1990s, the application of the sentinel node (SN) concept to gastrointestinal (GI) malignancies was not recognized because of the multidirectional and complicated lymphatic flow from the GI tract. However, several studies supporting the validity of the SN concept for GI cancers have been reported in the past 5 years. Because of its anatomical location, gastric cancer is one of the most suitable targets for minimally invasive surgery based on SN status. Laparoscopic local resection is theoretically feasible for curative treatment of SN-negative early gastric cancer. Although SNs in esophageal cancer are multiple and are distributed widely from the cervical to the abdominal area, selective and modified lymphadenectomy for clinically N0-stage esophageal cancer is likely to become feasible and clinically viable. Total mesorectal excision (TME) is accepted as a standard surgical procedure for rectal cancer. However, there is a risk of aberrant distribution of SNs beyond the extent of TME; for example, SNs may be lateral to the lower rectum. SN mapping with scintigraphy is useful for effective sampling of SNs in unexpected areas and accurate staging without extensive lymph node dissection. There are several practical issues to be overcome. The techniques and feasibility of laparoscopic SN sampling are still under investigation. Large-scale multicenter prospective validation studies for SN mapping in GI cancer are essential. If these remaining issues can be solved, SN mapping for GI cancer will have great clinical impact.