Flare Study - Fluorescence-Guided Lymphadenectomy for Augmented Retrieval and Evaluation in Rectal Cancer Surgery

In patients with mid-to-lower rectal cancer undergoing neoadjuvant chemoradiotherapy (NACRT), lymph node (LN) retrieval is frequently suboptimal, compromising accurate staging and prognostication. Fluorescence-guided surgery (FGS) using indocyanine green (ICG) has emerged as a technique to enhance lymphatic visualization in fibrotic post-radiation fields. This investigator--initiated, single-centre, quasi-experimental study analysed a prospectively maintained database (January 2023-December 2024). Patients undergoing peri-tumoral ICG tattooing followed by fluorescence-guided lymphadenectomy were compared with non-tattooed controls after 1:1 propensity score matching. The primary outcome was modification of lymphadenectomy extent. Secondary outcomes included LN yield, detection and positivity of aberrant lymph nodes, and nodal size. After matching, 46 patients were analysed in each group. Mean LN yield was significantly higher in the ICG group (14 ± 3.7 vs. 7 ± 3; P < 0.001). Fluorescence guidance altered the extent of lymphadenectomy in 23 patients (50%). Five aberrant lymph nodes (10.87%) were malignant and were predominantly small (mean size 4 ± 2 mm), located outside routine total mesorectal excision fields. Fluorescence-guided lymphadenectomy is feasible after NACRT and improves LN yield while facilitating detection of small aberrant nodes. These findings support its role as an adjunct to standard rectal cancer surgery, although validation in larger cohorts with long-term oncologic outcomes is required.