Fluorescence-Guided Surgery in the Combined Treatment of Peritoneal Carcinomatosis from Colorectal Cancer: Preliminary Results and Considerations.

Background: Indocyanine green (ICG) is a near-infrared fluorescent contrast agent, which preferentially accumulates in cancer tissue. The aim of our study was to investigate the role of fluorescence imaging (FI) with ICG (ICG-FI) for detecting peritoneal carcinomatosis (PC) from colorectal cancer (CRC).

Methods: Four CRC patients with PC scheduled for cytoreductive surgery + hyperthermic intraperitoneal chemotherapy were enrolled in this prospective study. At a median time of 50 min after 0.25 mg/kg ICG injected intravenously, intraoperative ICG-FI using Fluobeam was performed in vivo and ex vivo on all specimens. The Peritoneal Cancer Index was used to estimate the likelihood of complete cytoreduction.

Results: No severe complications were recorded. ICG-FI took a median of 20 min (range 10-30, IQR 15-25). Sixty-nine nodules were harvested. Fifty-two nodules had been diagnosed preoperatively by conventional imaging (n = 30; 43%) or intraoperatively by visual inspection/palpation (n = 22; 32%). With ICG-FI, 47 (90%) nodules were hyperfluorescent, and five hypofluorescent. Intraoperative ICG-FI identified 17 additional hyperfluorescent nodules. On histopathology, 16 were metastatic nodules. Sensitivity increased from 76.9%, with the conventional diagnostic procedures, to 96.9% with ICG-FI. The positive predictive value of ICG-FI was 98.4%, and test accuracy was 95.6%. Diagnostic performance of ICG-FI was significantly better than preoperative (p = 0.027) and intraoperative conventional procedures (p = 0.042). The median PCI score increased from 7 to 10 after ICG-FI (p < 0.001).

Conclusions: Our results suggest that intraoperative ICG-FI can improve outcomes in patients undergoing CS for PC from CRC. Further studies are needed to determine the role of ICG-FI in this patient population.