Herein, we evaluated the safety and efficacy of ICG-guided radical laparoscopic gastrectomy in patients with gastric cancer. Compared with routine laparoscopic gastrectomy, our data demonstrated that the ICG tracer-guided laparoscopic gastrectomy could significantly increase the number of lymph node dissections with similar short-term and long-term outcomes. Lymphadenectomy is crucial and challenging for surgeons. According to our study, ICG tracer-guided surgery may assist surgeon to perform safe and effective lymphadenectomy.
Due to the longer excitation wavelength, ICG under NIR imaging exhibits better tissue penetration and better lymph node visualization from hypertrophic adipose tissue compared to other dyes which observed by naked eyes9. Thence, the ICG-mediated NIR fluorescent imaging has been applied to identify lymphatic drainage and sentinel lymph nodes during laparoscopic gastrectomy21,22. Besides, perigastric lymph node dissection is essential for accurate pathological staging of gastric cancer and subsequent treatment, and is associated with the survival of patients23,24. ICG enables real-time observation of lymphatic vessels and lymph nodes, which is helpful for surgeons to perform a more thorough lymphadenectomy and en bloc resection to reduce intraoperative bleeding and vessel damage risk.
The effect of ICG on the number of retrieved lymph nodes is inconsistent according to previous studies. Lan et al. reported no difference in total number of lymph node retrieved from 14 ICG and 65 non-ICG patients17. Kwon et al. and Kim et al. found that ICG-guided laparoscopic gastrectomy is capable to retrieve more lymph nodes compared with routine surgery16,25. A recent randomized study demonstrated that ICG significantly improved the number of lymph node retrieved in D2 lymphadenectomy without increasing the risk of complications15. Our study consistently found that ICG could increase the number of lymph nodes retrieved during laparoscopic gastrectomy.
In our experience, the approach of ICG administration is a key factor that affects imaging quality. Traditionally, ICG administration includes subserosal and submucosal injections around the tumor14–17, 25. Previous studies suggested that submucosal injection is superior than subserosal injection in intraoperative lymph node detection14. And subserosal injection often caused ICG leakage and surgical field blur17. Therefore, we adopted submucosal injection of ICG in our study, Previous studies suggested preoperative injection of ICG15,16, since they assumed that it takes time for ICG to spread into lymph nodes and prolongs the operation time. Instead, we performed intraoperative injection, and our data showed similar operation time between ICG and non-ICG group. We assume that the visualization of lymph nodes by ICG could accelerate the lymph node dissection. Nevertheless, it remains to be determined the appropriate approach and timing of ICG administration in laparoscopic gastrectomy.
Our study found that ICG is not associated with increased incidence of perioperative complications, which is consistent with previous literature15–17, 25. We also found that the postoperative hospital stay was similar between two groups, which prompted similar recovery process. Our data shown similar incidence of short-term and long-term complications, and no patient suffered from reoperation due to postoperative complications. All above results confirmed the safety of ICG-guided laparoscopic gastrectomy.
We are aware of our potential limitations. First, this is a single-center center with limited sample size, which might bring selection bias. We performed PSM to minimize the selection bias and limitations that related to non-randomized and non-blinded property of this study. Further larger multicenter randomized studies are expected to confirm our findings. Second, it requires longer follow-up period to evaluate long-term outcomes, especially relapse-free survival and cumulative survival rates.