Diagnostic validity of radio-guided sentinel node mapping for gastric cancer: a review of current status and future direction.

Diagnostic validity of sentinel node (SN) mapping has been recently introduced into the field of various solid tumors, including gastrointestinal (GI) cancer. In gastric cancer, acceptable detection rates of SNs, as well as sensitivity in detecting micrometastasis based on SN status, was reported using the dye-guided method, as well as the radio-guided method. Gastric cancer is currently one of the suitable targets of SN navigation surgery among visceral tumors. Despite the multi-directional and complicated lymphatic flow from gastric mucosa, the anatomical situation of the stomach is relatively suitable for SN mapping in comparison with organs embedded in closed spaces, such as the esophagus and rectum. In particular, clinically T1N0 gastric cancer seems to be a good entity for which to try to modify the therapeutic approach. From the data reported in the literature, micro-metastases tend to be limited within the sentinel basins in cT1N0 gastric cancer. Sentinel basins are, therefore, good targets of selective lymphadenectomy for cT1N0 gastric cancer with the potential risk of micrometastasis. Furthermore, laparoscopic local resection is theoretically feasible for curative treatment of SN negative early gastric cancer. For laparoscopic application of SN mapping of gastric cancer, a radio-guided method is essential. Although recent single institutional studies support the validity of the SN concept, a multi-centric prospective validation study based on a standardized protocol is essential for further clinical application. Currently, two major well-designed clinical trials of SN mapping for gastric cancer open surgery have been initiated in Japan. Radio-guided SN mapping for gastric cancer has a great potential to provide a new paradigm shift for surgical management of an early gastric cancer.