Fluorescence Imaging After Indocyanine Green Injection for Detection of Peritoneal Metastases in Patients Undergoing Cytoreductive Surgery for Peritoneal Carcinomatosis From Colorectal Cancer

Objective: The aim of this study was to evaluate the role of fluorescence imaging (FI) using an intraoperative injection of free indocyanine green (ICG) in the detection of peritoneal metastases (PM) due to colorectal cancer (CRC). Background: A large proportion of patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy will have local recurrence. This is, in part, related to the presence of small undetected nodules in the peritoneal cavity. Near-infrared FI-guided surgery has provided new opportunities for detection of nonvisible lesions during cancer surgery. Methods: Patients with PM from CRC admitted for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy were selected for participation in this study (NCT02032485). Free ICG, at 0.25 mg/kg of patient weight, was intravenous (IV)-injected intraoperatively. Tumor-to-background ratio was calculated for all suspect resected PM. Results: Sixty-three of 78 peritoneal resected nodules in 14 patients were evaluated for fluorescence, among them, 53 were malignant (84%) and 10 benign (16%). Twenty-six were hypofluorescent, 16 moderately hyperfluorescent, and 21 hyperfluorescent. Amongst the 42 nodules of the 9 patients with nonmucinous adenocarcinoma, the mean tumor-to-background ratio was 1.92 (SD 0.67) in malignant and 1.02 (SD 0.06) in benign nodules (P = 0.0099). In 4 of 14 patients (29%), the surgery was modified by intraoperative ICG-FI, which detected additional PM not found using visualization and palpation. Conclusions: This pilot study demonstrates that non-mucinous PM of CRC can be visualized intraoperatively using ICG-FI. Furthermore, ICG-FI findings resulted in modification of the planned surgery in 29% of patients.