Interim results and safety assessment of indocyanine green peritumoral injection for regional lymphatic outflow area mapping in colon cancer as a part of the ISCAPE TRIAL

Abstract

To determine whether the boundaries of the lymphatic outflow area, mapped with indocyanine green, match the lymphogenic metastasis area according to the surgical specimens' pathological study. From 26.07.2022 to 13.02.2023, 27 patients with resectable colon cancer were included in the study; 25 of them underwent intraoperative imaging of the lymphatic outflow from the affected area of the intestine using the peritumoral injection of indocyanine green, assessment of infrared light fluorescence, followed by a comparison of the glow area with a pathologically defined zone of lymphogenic metastasis. Of the 25 mapping procedures, 17 (68%) were typical (no deviations from the standard injection schedule and solution extraperitonization); in 8 (32%) cases, there were technique defects. No allergic reactions to indocyanine or side effects were observed. Of the 25 patients who received peritumoral indocyanine green, 17 (68%) had no complications during the postoperative period. There were no postoperative deaths. Technique defects during the injection did not interfere with the outcome interpretations: all patients showed the indocyanine green fluorescence within the paracolic basin proximal and distal to the tumor; fluorescence along the main feed vessel was recorded in 24 (96%) patients. Fluorescence of the aberrant lymphatic vessels was reported in 3 (12%) cases and required extension of the resection in 1 patient. The time to the indocyanine green appearance in the D1 basin lymphatic vessels and along the main feed vessel varied widely (from 15 minutes to 1 hour or more). It was also noted that the boundaries of indocyanine distribution varied significantly (from 3 to 16.3 cm) depending on individual characteristics. The analysis of pathological data showed no cases of secondary involved lymph nodes beyond the boundaries of indocyanine distribution. In most cases, secondary altered paracolic lymph nodes were localized directly in the projection of the tumor, and concomitant lesions of mesocolic nodes were more common than metastatic lesions of D1 nodes located laterally from the tumor. The study results show that mapping the regional lymphatic basin is a reproducible and feasible technique. It does not increase the rate of complications and contributes to identifying individual lymphatic outflow characteristics to ensure oncological radicality in non-standard lymphatic anatomy.