Staging LaParoscopy to Assess Lymph NOde InvoLvement in Advanced GAstric Cancer

The SN assessment will be conducted similarly to the method proposed by Märkl et al. All LNs will be stored in a -80 °C freezer, immediately after retrieval. Within 1 to 3 days, each LN will be individually measured and weighed. Small LNs (\<5 mm in short diameter) will be bisected, and half of the node will be processed for histological evaluation while the remaining half will be used for OSNA analysis. For intermediate-sized LNs (5-10 mm), a middle slice of about 2 mm thickness will be cut out for the histology, and the remaining parts of the node will be processed by OSNA. In large LNs (\>10 mm), at least two slices will be cut out for histology, and the remaining parts of the node will be analyzed by OSNA.

Pneumoperitoneum (10-12mmHg) will be obtained with Veress needle or 10mm trocar after minilaparotomy. Peritoneal cavity will be thoroughly assessed after insertion of two additional trocars. In cases of macroscopic dissemination, peritoneal cancer index (PCI) will be determined. After switching the optical camera into near-infrared / indocyanine green fluorescence mode, the primary tumor will be visualized, followed by assessment and possible dissection of sentinel lymph node with a high-energy device. The lymph node will be retrieved with a sterile bag, and the area of dissection will be marked with a clip. Trocars will be removed under visual assistance, and the pneumoperitoneum will be released through trocars in order to prevent port-site metastases.

Patients will undergo gastroscopy one day prior to staging laparoscopy. The ICG powder contains 0.125 mg/ml. Two milliliters of ICG (0.125mg/ml) solution is injected in the submucosa with into four peritumoral sites, 0.5 ml for each site.