Dr. Kemeny has provided us with a current and comprehensive review of the management of liver metastases from colorectal cancer. The explosion of new oral and intravenous chemotherapy agents along with novel molecularly targeted agents have revolutionized the treatment of colorectal cancer but has challenged clinicians to develop new treatment algorithms that offer patients the most effective multidisciplinary treatment.
Hepatic Resection
Despite the new chemotherapy agents, hepatic resection is still the most effective therapy for metastatic colorectal cancer confined to the liver. Multiple large series have shown that liver resections can be performed with low (< 5%) mortality and can offer long-term cure to about 30% of patients with metastatic cancer. As the safety of hepatic resection has evolved, major centers have adopted more aggressive surgical approaches to this disease. Patients with multiple, bilobar, and very large hepatic metastases now routinely undergo resection as long as there is no extrahepatic disease and adequate hepatic reserve.
With this expansion of surgical indications, scoring systems proposed by Dr. Fong and others looking at specific preoperative prognostic factors can predict long-term outcomes based on the size of the largest tumor, the preoperative carcinoembryonic antigen, the number of tumors, the nodal status of the primary tumor, and the disease-free interval. These scoring systems should not be used to exclude patients from hepatic resection, but rather, to stratify patients in clinical trials.
Ablation
To compliment resectional strategies when complete resection of all metastases is not possible, a number of ablative techniques have been explored. Currently, the most widely used technique is radiofrequency ablation (RFA), which has been shown to be a safe, feasible treatment for hepatic metastases. RFA can be performed percutaneously or laparoscopically, alone or in combination with an open hepatic resection.
Due to the risks of biliary stricture, lesions near the central hepatic hilum should not be ablated. Tumors close to the diaphragm, near the dome, or abutting the stomach or colon should also not be ablated due to the risk of injury to these structures. A frustrating limitation of RFA is the inability to monitor the ablation in real time, necessitating a series of follow-up computed tomography scans to determine whether an adequate ablation has been accomplished.
Curley et al reviewed a series of 418 patients who underwent hepatic resection, RFA, or chemotherapy.[2] Hepatic resection produced significantly better overall survival (65% at 4 years) compared to RFA and resection (36% at 4 years) or RFA alone (22% at 4 years). Intrahepatic and local recurrences were markedly increased in the RFA patients compared to those with hepatic resection. Despite the selection bias, hepatic resection and RFA produced superior survival compared to the group undergoing chemotherapy. This study supports the fact that RFA cannot be considered equivalent to hepatic resection but may complement surgical treatment of unresectable bilobar tumors or tumors in difficult locations.
Adjuvant Chemotherapy After Hepatic Resection
Randomized trials examining the role of adjuvant fluorouracil(Drug information on fluorouracil) (5-FU) and leucovorin after hepatic resection compared to no treatment have been negative. Current studies are addressing the use of new agents alone or with molecularly targeted agents, although many medical oncologists are already treating patients postoperatively with these systemic regimens. We await further objective evidence to justify treating these patients with adjuvant systemic therapy.
