In Search for Optimal Targets for Intraoperative Fluorescence Imaging of Peritoneal Metastasis From Colorectal Cancer

Abstract

Peritoneal metastasis (PM) occurs in about 10% of patients with colorectal cancer (CRC). Fluorescence imaging can enhance contrast between cancerous and benign tissue, enabling the surgeon to clearly visualize PM during cytoreductive surgery. This study assessed the suitability of different biomarkers as potential targets for tumor-targeted imaging of PM of CRC. Tissue samples from primary tumor and PM from patients with CRC were obtained from the pathology archives and immunohistochemical stainings were performed. Overexpression of the epithelial cell adhesion molecule (EpCAM) and carcinoembryonic antigen (CEA) was seen in 100% of PM samples and the expression was strong in >70% of samples. Tyrosine-kinase Met (C-Met) and folate receptor α overexpression was seen in 20% of PM samples. For successful application of tumor-targeted intraoperative fluorescence imaging of PM, biomarkers need to be identified. We demonstrated that both EpCAM and CEA are suitable targets for fluorescence imaging of PM in patients with CRC.

Keywords: Image-guided surgery; biomarkers; colorectal cancer; fluorescence; metastasis; peritoneal metastasis.

Figure 1.

Representative epithelial and stromal staining intensities in peritoneal metastasis from colorectal cancer using immunohistochemistry (as specified in the Methods section) at zoom 10x after immunohistochemistry. Examples of (A) strong 3+ epithelial staining intensity (CEA), (B) moderate 2+ epithelial staining intensity (C-Met), (C) weak 1+ epithelial staining intensity (C-Met), (D) absent 0 epithelial staining (FRα), (E) absent 0 stromal staining (EpCAM), (F) weak 1+ stromal staining (C-Met), and (G) moderate 2+ stromal staining (CEA). CEA indicates carcinoembryonic antigen; FRα, folate receptor α.