Background: The goal of this study was to evaluate the feasibility and accuracy of sentinel node (SN) mapping with endoscopic submucosal blue dye injection during laparoscopic distal gastrectomy for gastric cancer.
Methods: Thirty-four patients affected by gastric adenocarcinoma without gross clinical serosal invasion and distant metastasis were prospectively enrolled. At the start of the surgery, 2 ml of 2% patent blue was endoscopically injected into the submucosal layer at four points around the site of the primary tumor. Sentinel nodes were defined as nodes that were stained by the blue dye within 5-10 min after the dye injection. After identification and removal of sentinel lymph nodes, each patient underwent laparoscopic distal gastrectomy with D1 (n = 2) or D2 (n = 32) lymphadenectomy.
Results: Of the 34 patients, 14 had positive nodules (41%). SNs were detectable as blue nodes in 27 (80%) of 34 patients. The mean number of dissected lymph nodes per patient was 31 +/- 10 (range = 16-64) and the mean number of blue nodes was 1.5 (range = 1-4). Only five (sensitivity 36%) of 14 N(+) patients had at least one metastatic lymph node among the SNs identified. In these 14 patients the sentinel node was traced in 12 cases. Sentinel node status diagnosed the lymph node status with 74% accuracy. In early gastric cancer (n = 18), three patients had lymph node metastasis. These early gastric cancer patients with nodal metastases had at least one metastatic lymph node among the SNs identified (sensitivity 100%).
Conclusions: Blue dye SN mapping during laparoscopic distal gastrectomy seems to be a feasible and accurate diagnostic tool for detecting lymph node metastasis in patients with early-stage gastric cancer in which the accuracy of the method was 100%. However, in more advanced gastric cancer the results are not satisfactory. Validation of this method requires further studies on technical issues, including selection of the tracers.