Clinical significance of sentinel lymph node detection in early gastric carcinoma using fluorescent beads and dye for the less invasive surgery *
Introduction: If the sentinel node（SN）detection were possible in the early stage of gastric cancer, less invasive surgery to preserve function might be realized. Many reports on SN navigation surgery for gastric cancer patients have been published, and various tracers have been presented and discussed. We have used fluorescent beads because the particle diameter is nearer to that of a cancer cell than that of other tracers. The dye method（Indocyanine Green;ICG）was applied with or without fluorescent beads. The micrometastasis of resected lymph nodes was investigated in past cases to clarify its clinical significance for survival. Methods:Ninety-two cases with gastric cancer were enrolled. These cases were categorized into three groups according to the method used;cases using the fluorescent beads / ICG method, one using ICG alone（early period）and ones using ICG alone（late period）, of which there were 31, 29 and 32 cases, respectively. One day before the operation, fluorescent beads were injected into the submucosal layer around the primary lesion endoscopically. During the operation, ICG was injected into the subserosal space from the serosal side surrounding the primary lesion. After the injection of ICG, a green SN was detected from 5 to 15 minutes later. The green nodes were dissected, and then a gastrectomy was performed with the standard lymphadenectomy. Ultraviolet irradiation was used for extracted lymph nodes and shiny nodes were assumed to be SN. All resected lymph nodes were submitted to investigation for micrometastasis using an anticytokeratin antibody（AE1/AE3）. Furthermore, to investigate the clinical significance, 1475 lymph nodes of pT1pN1 / pT2pN1 and 1591 lymph nodes of pT2pN0 were submitted to investigation a micrometastasis for compare the survival rates of cases with and without micrometastasis. Results:The SN detection rates of early gastric cancer cases with the fluorescent bead / ICG method, ICG alone（early period）and ICG alone（late period）were 92％（23/25）, 76.1％（16/21） and 96.1％ （25/26） respectively. The accuracy rate of them was 95.4％, 93.7％ and 96％, respectively. In the late period, we had two cases with lymph node metastasis. In one case, the metastases were detected in SN. In other case, it was detected in SN and SN station. Regarding micrometastasis, there was one case out of SN station. However, the existence of micrometastasis to dissected lymph nodes did not contribute to the difference in survival. Conclusions:The SN detection rate increased when the fluorescent beads method was combined with the ICG method. However, it was difficult to detect a fluorescent lymph node hidden in adipose tissue during an operation because of the autofluorescence of the adipose tissue. Detection of SN using ICG alone was possible and revealed relatively high rate. Besides the one case with micrometastasis outside on SN station, local resection of the gastric primary lesion with lymph node dissection of the SN station might be possible and meaningfull as a less invasive surgery because the existence off micrometastasis did not contribute to worsening of survival.(Accepted on October，2007)
