Visceral Fat and Indocyanine Green-Guided Lymph Node Dissection During Laparoscopic Radical Gastrectomy: A Post Hoc Analysis of a Randomized Controlled Trial

Authors
Yi-Hui Tang, Ze-Ning Huang, Jian-Xian Lin, Chao-Hui Zheng, Chang-Ming Huang

Affiliations
Department of Gastric Surgery, Fujian Medical University Union Hospital, Fuzhou, China

Background
Indocyanine green (ICG) fluorescence imaging improves the quality of lymph node (LN) dissection in patients with gastric cancer (GC); however, its application in patients with visceral obesity remains unclear. This study aimed to explore the impact of visceral fat area (VFA) on the short- and long-term efficacy of ICG-guided laparoscopic D2 lymphadenectomy for GC.

Methods
A post hoc analysis was performed in patients who participated in a phase 3 randomized clinical trial of ICG-guided laparoscopic radical gastrectomy versus conventional laparoscopic radical gastrectomy from November 2018 to July 2019. The VFA was calculated based on preoperative CT images for each patient. Short-term efficacy included the quality of LN dissection and surgical outcomes, while long-term efficacy included overall survival (OS) and recurrence-free survival (RFS).

Results
This study included 126 patients each in the ICG (high-VFA, n=43) and non-ICG groups (high-VFA, n=38). Compared with the non-ICG group, the ICG group had significantly more retrieved LNs and a significantly lower LN noncompliance rate (P <0.05). In the non-ICG group, a high VFA was significantly associated with fewer retrieved LNs (37.5 vs. 43.9, P = 0.001), a higher LN noncompliance rate (73.7% vs. 50.0%, P = 0.014), more intra-abdominal infections (2.3% vs. 13.2%, P = 0.026), and a prolonged postoperative hospital stay (P = 0.009). For the ICG group, total retrieved LNs (49.6 vs. 50.1, P = 0.846), LN noncompliance (32.6% vs. 32.5%, P = 0.997), postoperative recovery (P >0.05), and postoperative morbidity (P >0.05) were comparable in patients with high-VFA versus those with low-VFA. Regardless of the VFA, the 3-year OS (RFS) was better in the ICG group than in the non-ICG group (low-VFA: 83.1% [76.9%] vs. 73.9% [67.0%]; high-VFA: 90.7% [90.7%] vs. 73.7% [73.5%]; P for interaction = 0.474 [0.547]).

Conclusion
The short- and long-term efficacies of ICG tracing were not influenced by visceral obesity. This technique should be routinely used in laparoscopic radical gastrectomy for GC.