164. INTRAOPERATIVE LYMPHATIC FLOW MAPPING USING INDOCYANINE GREEN PREDICTS LYMPH NODE METASTASIS IN ESOPHAGEAL CANCER PATIENTS NOT TREATED WITH NEOADJUVANT CHEMOTHERAPY

Abstract

Abstract Background Lymphatic flow mapping using near-infrared fluorescence (NIR) imaging with indocyanine green (ICG) has been used for the intraoperative prediction of lymph node metastasis (LNM) in various cancers. Previous studies examined the feasibility of applying this technique to patients with esophageal cancer. However, a consistent method that yields sufficient diagnostic quality has yet to be confirmed. This study explored the diagnostic utility of our established lymphatic flow mapping protocol for predicting LNM in esophageal cancer. Methods We injected 0.5 mL of ICG (500 μg/mL) into the submucosal layer at four peritumoral points on the day before surgery for 54 patients. We performed lymphatic flow mapping intraoperatively using NIR imaging. After determining the NIR status and presence of metastases, evaluable lymph node stations on intraoperative NIR imaging and all resected lymph nodes were divided into four categories: ICG + meta+ (true positive), ICG + meta− (false positive), ICG − meta+ (false negative), and ICG − meta− (true negative). Logistic regression models were used to investigate the characteristics of patients with LNs or LN stations associated with high false-negative rates. Results The distribution of ICG+ and meta+ lymph node stations differed according to the primary tumor site. Sensitivity and specificity for predicting meta+ lymph nodes among ICG+ ones were 50% and 75%, respectively. Predicting meta+ lymph node stations among ICG+ stations improved these values to 66% and 77%, respectively. Undergoing neoadjuvant chemotherapy was an independent risk factor for having meta+ lymph nodes with false-negative diagnoses (odds ratio: 4.82; 95% confidence interval: 1.28–18.19). The sensitivity of our technique for predicting meta+ lymph nodes and meta+ lymph node stations in patients who did not undergo neoadjuvant chemotherapy was 79% and 83%, respectively. Conclusion Our NIR imaging protocol potentially helps to predict lymph node metastasis intraoperatively in patients with esophageal cancer undergoing esophagectomy who had not undergone neoadjuvant chemotherapy. This technique may effectively serve as a parameter for assessing the need for dissecting LNs in each station and determining whether it is applicable to reduce the extent of lymphadenectomy.