The Clinical Potential of FBPA-PET/CT Imaging for Colorectal Cancer and its Liver Metastases Expressing LAT1

Background/Aim: 18F-fluoro-deoxy-glucose positron emission tomography (18F-FDG PET) has become indispensable for staging colorectal cancer but has limitations. Thus, PET with a focus on metabolism other than glucose, mainly amino acid metabolism, has been developed. L-type amino acid transporter 1 (LAT1) is known to be a cancer-specific amino acid transporter and, although 4- Borono-2-(18)F-fluoro-phenylalanine (FBPA) has been reported to be useful as a probe for LAT1, the significance of LAT1 expression in colorectal cancer is ambiguous and implementation of 18F-FBPA-PET in colorectal cancer has not yet been reported. Materials and Methods: The aims of this study were to investigate the expression of LAT1 in primary lesions and metastatic lesions of colorectal cancer by immunohistochemical analysis and report the initial experience of performing 18F-FBPA-PET on colorectal cancer patients in clinical practice. Results: There was a significant correlation between LAT1 protein expression in primary tumors and liver metastases. Furthermore LAT-1 expression was positively correlated with recurrence (p=0.033). We performed 18F-FBPA-PET on three rectal cancer patients and detected cancer. Conclusion: LAT1 protein is expressed not only in the primary colorectal tumor, but also in liver metastases. 18F-FBPA-PET can be safely performed in patients with colorectal cancer.