Prognostic Impact of Fluorescent Lymphography on Gastric Cancer After Neoadjuvant Chemotherapy

Importance Indocyanine green (ICG)-guided lymphadenectomy has been increasingly used to treat gastric cancer. However, its oncologic impact remains unclear. Objective To investigate the effect of ICG tracing on long-term outcomes in patients diagnosed with locally advanced gastric cancer undergoing neoadjuvant chemotherapy (NAC) followed by laparoscopic radical gastrectomy. Design, Settings, and Participants This retrospective cohort study included patients diagnosed with cT2-4N0/+M0 gastric adenocarcinoma who underwent NAC and laparoscopic radical gastrectomy at 3 teaching hospitals in China between January 2015 and June 2021, with follow-up data examined until June 2024. Overlap weighting (OW) was used to compare outcomes between the ICG and non-ICG groups. Results were tested for robustness using propensity score matching (PSM) and instrumental variable analysis. Exposure ICG-guided lymphadenectomy during laparoscopic gastrectomy. Main Outcomes and Measures The primary end points were 3-year survival outcomes, including overall survival (OS) and recurrence-free survival (RFS). Results Data from 459 patients (338 men [73.6%] and 121 women [26.4%]; mean [SD] age, 60.8 [9.9] years), of whom 119 underwent ICG-guided lymphadenectomy, were included. After OW adjustment, the ICG group exhibited a higher number of lymph nodes harvested (47.4 vs 38.3; P < .001) and better 3-year OS (78.6% vs 66.6%; P = .04) and RFS (74.0% vs 57.0%; P = .03) compared with the non-ICG group. Multivariable Cox regression analysis revealed that ICG tracing was an independent prognostic factor for both OS (hazard ratio, 0.59; 95% CI, 0.39-0.90; P = .02) and RFS (hazard ratio, 0.59; 95% CI, 0.40-0.87; P = .01), with the results remaining significant in both doubly robust and instrumental variable-adjusted models. Furthermore, in the OW-adjusted population, the OS benefit of ICG tracing was more pronounced in subgroups with ypN2/3 gastric adenocarcinoma (70.3% vs 36.2%; P = .01) and those achieving major pathological response (97.7% vs 77.6%; P = .04) (both P for interaction = .04). Similar results were obtained after adjusting for PSM. Conclusion and Relevance In this study, ICG tracing was associated with enhanced lymphadenectomy and improved survival outcomes in patients with locally advanced gastric cancer after NAC. A prospective randomized clinical trial is needed to verify these findings.