Interim results of sentinel node biopsy during laparoscopic gastrectomy: Possible role in function-preserving surgery for early cancer

Introduction: Intraoperative detection of sentinel nodes (SNs) has been used clinically to predict regional lymph node (LN) metastasis in patients with breast cancer and malignant melanoma. Intraoperative lymphatic mapping and SN biopsy can potentially be combined with minimally invasive surgery. However, few reports have demonstrated the validity of SN biopsy during laparoscopic gastrectomy. The aim of this study was to investigate the feasibility and accuracy of laparoscopic lymphatic mapping in predicting LN status in patients with gastric cancer. Methods: A total of 35 patients with gastric cancer diagnosed preoperatively as T1, N0 were enrolled. Endoscopic injection of technetium-99m-radiolabeled tin colloid was completed 16 hours before surgery, and radioactive SNs were identified with a gamma probe intraoperatively. Isosulfan blue dye was injected endoscopically during the operation. Laparoscopy-assisted gastrectomy with LN dissection was performed. All resected LNs were evaluated by routine pathology examination. Results: SNs were detected in 33 (94.3%) of 35 patients. The mean number of SNs was 3.9, and the diagnostic accuracy according to SN status was 97.0% (32/33), as one patient with a false-negative result was observed. The patient with the false-negative specimen was finally diagnosed as having advanced gastric cancer with invasion into the proper muscular layer and severe lymphatic vessel invasion, causing destruction of normal lymphatic flow by the tumor. Conclusions: Radio-guided SN mapping during laparoscopic gastrectomy is an accurate diagnostic tool for detecting lymph node metastasis in patients with early-stage gastric cancer. Validation of this method requires further studies on technical issues, including indications, tracers, methods of lymph node retrieval, and diagnostic modalities of metastasis.