Indocyanine green fluorescence imaging for lymph node detection and long-term clinical outcomes in colorectal cancer surgery: A systematic review and meta-analysis

Background: The indocyanine green fluorescence imaging (ICG-FI) technique is increasingly being used in laparoscopic colorectal surgery for lymph node mapping. However, there is no definitive standard regarding whether the application of this technique can significantly increase the detection rate of metastatic lymph nodes and improve long-term prognosis.

Methods: PubMed, Embase, Web of Science, and Cochrane Library databases were searched to include studies including ICG-FI in laparoscopic colorectal surgery. Data on the detection rate of lymph nodes, metastatic rate of ICG-positive nodes, and long-term clinical outcomes were extracted following inclusion criteria.

Results: Eighteen studies with a total of 1552 patients 922 with ICG-guided laparoscopic and 630 without ICG technique were finally included. Clinical stage II/III colorectal tumors were the most commonly studies types. The patients using the ICG-FI technique had more harvested lymph nodes (weighted mean: 23.5 vs. 18.9; WMD = 4.6; p < 0.00001) during dissection but a lower metastasis rate of ICG-positive nodes (61/218 [28%] vs. 96/333 [28.9%]; OR = 1.45; p = 0.08). Compared with conventional laparoscopic colorectal surgery, additional ICG-FI technique did not improve the 3 year overall survival rate (272/289 [94.1%] vs. 269/289 [93.1%]; OR = 1.19; p = 0.61), relapse-free survival (246/289 [85.1%] vs. 249/289 [86.2%]; OR = 0.92; p = 0.72), and local recurrence rate (22/289 [7.6%] vs. 28/289 [9.7%]; OR = 0.77; p = 0.38). The overall detection rate of sentinel lymph nodes, lymph flow, and metastatic rate of ICG-positive nodes with the help of ICG-FI were 86.8%, 89.9%, and 22.8%, respectively. No patients experienced major adverse events during ICG injection preoperatively or postoperatively.

Conclusions: Indocyanine green fluorescence imaging-guided procedure, compared to conventional laparoscopic dissection, can assist in obtaining a greater number of harvested lymph nodes and metastatic lymph nodes, however, it did not significantly improve the long-term clinical outcomes.

Level of evidence: Level III systematic review of randomized control and nonrandomized studies.