MANAGEMENT OF COLORECTAL LIVER METASTASES

Abstract

Colorectal cancer is the most common gastrointestinal malignancy all over the world. As with many types of cancer, death from colorectal cancer is often a result of metastatic disease. Over one-half of patients who die of colorectal cancer have liver metastases at autopsy, and the majority of these patients die as a result of their metastatic liver disease. But unlike many other types of cancer, the presence of distant metastases from colorectal cancer does not preclude curative treatment. Resection of hepatic metastases from colorectal cancer offers the best chance of long-term survival. Unfortunately the majority of patients with colorectal hepatic metastases are not suitable for resection and therefore specific criteria should be used to select those who may benefit from such intervention. In patients with colorectal cancer, synchronous liver metastases may be detected during preoperative testing or identified intra-operatively during colectomy. Metachronous liver metastases may be suspected at some point after colectomy. In patients who are candidates for surgical resection of their liver metastases, the goals of preoperative assessment are: A) to exclude the presence of extrahepatic disease; B) to delineate the anatomy of the metastases, and C) to determine the ability of the patient to tolerate hepatic resection. Preoperative evaluation requires a complete medical evaluation to determine the patient’s suitability for surgery as well as detailed anatomic imaging to determine the location of the liver tumors and to exclude extra hepatic metastases. Radiological evaluation is needed not only to identify extrahepatic disease but also to assess the adequacy of liver parenchyma after surgery. In addition to the patient evaluation, liver function tests are evaluated to assess the synthetic function of the liver; combined with radiological findings, these tests can aid in the decision-making process. Many different non-invasive imaging modalities are available for the visualization of liver metastases. The options include computed tomography, magnetic resonance imaging, ultrasound and positron emission tomography using fluorine-18 labeled fluorodeoxy-glucose. The acceptance of surgical resection as standard treatment for hepatic colorectal metastases is based on the increasing safety of major liver resections, and on the growing body of data demonstrating that when metastases are isolated in the liver, resections can be potentially curative. The increasing safety of liver resection can be attributed to advances in different areas including marked advancements in medical imaging allow better patient selection and surgical planning, advancements in understanding of physiology have enhanced the safety of anesthetic and preoperative care and studies of hepatic anatomy and physiology have resulted in improved surgical techniques. In the absence of treatment, the prognosis for patients with hepatic colorectal metastases is dismal, with 5-year survival rates of 3% or less. There is no role for palliative liver resections (incomplete resections of hepatic metastases) as there do not prolong survival. It is therefore of major relevance to localize accurately all hepatic lesions before performing surgical resections. This is also important to plan an adequate resection. To improve the results of surgery, a subgroup of these patients either receive neoadjuvant or adjuvant chemotherapy. Patients not suitable for surgery, due to extensive liver metastases or extrahepatic diseases, in general undergo systemic chemotherapy. Several newer therapies such as cryosurgery, radiofrequency ablation, portal vein embolization and isolated hepatic perfusion and regional chemotherapy are being evaluated in patients not suitable for surgery due to the number or distribution of liver metastases.