Surgery is the only curative option for patients with liver metastases of colorectal cancer, but few patients present with resectable hepatic lesions. Chemotherapy is increasingly used to downstage initially unresectable disease and allow for potentially curative surgery. Standard chemotherapy regimens convert 10%-20% of cases to resectable disease in unselected populations and 30%-40% of those with disease confined to the liver. One strategy to further increase the number of candidates eligible for surgery is the addition of active targeted agents such as cetuximab and bevacizumab to standard chemotherapy. Data from a phase Ⅲ trial indicate that cetuximab increases the number of patients eligible for secondary hepatic resection, as well as the rate of complete resection when combined with first-line treatment with the FOLFIRI regimen. The safety profiles of preoperative cetuximab or bevacizumab have not been thoroughly assessed, but preliminary evidence indicates that these agents do not increase surgical mortality or exacerbate chemotherapyrelated hepatotoxicity, such as steatosis (5-fluorouracil), steatohepatitis (irinotecan), and sinusoidal obstruction (oxaliplatin). Secondary resection is a valid treatment goal for certain patients with initially unresectable liver metastases and an important end point for future clinical trials.
INTRODUCTIONGlobally, one half of the nearly 1 million patients diagnosed with colorectal cancer annually will develop liver metastases during the course of the disease [1,2] . Autopsy findings suggest that approximately 50% of patients who die of colorectal cancer have liver metastases, which are the only site of metastatic disease in approximately 20%-30% of patients [3] and the cause of death in most of these patients [4] . In other types of cancer, liver metastases are a sign of distant dissemination, and surgery is not a curative option [5] . In colorectal cancer, however, portal vein drainage from the gastrointestinal tract to the liver favors metastasis to the liver without systemic dissemination [5] . Surgery therefore provides a potentially curative treatment option for patients with resectable liver disease [6] , in contrast with palliative chemotherapy for those with unresectable disease.One of the most important recent advances in the management of advanced colorectal cancer is the concept of downstaging initially unresectable disease using chemotherapy so that more patients become eligible for potentially curative surgery. Current treatment guidelines [4] and substantial research highlight the importance of increasing the rates of secondary resection in initially unresectable disease. The addition of active targeted therapies, such as cetuximab and bevacizumab, to chemotherapy may further increase secondary resection rates. This article summarizes the current data on secondary resection of initially unresectable liver metastases of colorectal cancer using currently available systemic therapy regimens.
HOW RESECTABILITY MAY BE
ACHIEVEDReported 5-year survival r...