Liver Metastases from Colorectal Cancers

Colorectal cancer is the third most common malignancy in both sexes with increasing incidence with age. In 2010, approximately 142,570 new cases of colorectal cancer (CRC) will result in it being the second leading cause of cancer death in the United States. Approximately 70-80% of patients with CRC are surgically treated with curative intent. The overall survival at 5 years is 67%. Approximately 25% of patients will have hepatic metastases at the time of diagnosis and an additional 25% will later develop hepatic metastases. About 14,000 (20%) of patients will die annually with metastases to the liver as the only site of disease spread. Selective hepatic resection is the only curative therapy for these patients, but it has a high mortality rate (2-7%). Therefore careful pre-resection screening is crucial to avoid futile partial hepatectomy. Imaging has a central role in accurate staging of CRC, via liver ultrasound, CT of the chest, abdomen and pelvis, MRI of the liver and whole-body 18FFDG PET/CT, with each imaging modality having a proper role. The single best imaging modality for detection of intra- and extra-hepatic metastases is ¹⁸F-FDG PET/CT. ¹⁸F-FDG PET/CT can also be used to evaluate early treatment response. ¹⁸F-FDG PET does have limitations including false-positives due to treatment induced inflammation and false negatives from poor ¹⁸F-FDG uptake in CRC with a high mucinous component or the transient effects of chemotherapy. Despite these limitations, 18F-FDG PET/CT is a valuable tool in the evaluation of liver metastases from colorectal cancer.

Keywords: Colorectal cancer; Hepatic metastases; ¹⁸F-FDG, PET/CT.