Quantitative Detection of CEA mRNA in the Smog and Tissue Exudate Whole Process Collected During Laparoscopic (Robotic) Radical Gastrectomy in Gastric Cancer Patients: Study Protocol for a Single Center Prospective, Single-arm, Longitudinal Pilot Study（SMOG 01Study）

Cytological examination of peritoneal lavage fluid has become an important parameter for pathological staging and prognosis judgment of gastric cancer. However, the vast majority of previous studies have only focused on collecting peritoneal lavage fluid through laparotomy or laparoscopic exploration for cytological and tumor marker monitoring as further tumor staging. Unfortunately, there is no research focusing on whether laparoscopic (or robotic) surgery under the carbon dioxide pneumoperitoneum environment can cause the iatrogenic spread of cancer cells, and there is also a lack of a practical and feasible method to collect smog and tissue exudates generated throughout the entire surgical process for cytological monitoring, to determine whether laparoscopic surgery itself may cause the iatrogenic spread of tumor cell, to uncover the potential mechanisms and propose appropriate preventive measures of peritoneal metastasis. Therefore, the investigators have designed a special device to collect smog and tissue exudates generated during laparoscopic or robotic radical gastrectomy to determine whether there is a possibility of iatrogenic cancer cell dissemination in the abdominal cavity throughout the entire course of laparoscopic or robotic surgery by using RT-PCR to detect CEA mRNA, which can become one of the reasons for gastric cancer peritoneal metastasis.