Radiofrequency ablation of unresectable liver metastases.

Abstract

The most common hepatic metastasis among adults in the United States is from colorectal cancer, the fourth most frequent malignancy, with approximately 130,200 new cases expected in 2000. Liver metastasis will develop within 5 years of initial diagnosis in about half these patients, and approximately 20% will, at first, have no extrahepatic metastases. Note also that the liver is the sole metastatic site in about 25% of deaths from colorectal cancer. Pancreatic neuroendocrine tumors are the second most common origin of metastasis confined to the liver. Other cancers, such as those of the lung, breast, stomach, and cutaneous melanoma, usually disseminate simultaneously to the liver and multiple other visceral sites. Occasionally, gastrointestinal sarcoma or ocular melanoma and, more rarely, renal cell carcinoma, Wilms’ tumor, or breast cancer, may initially metastasize to the liver alone. Survival of patients with liver metastasis is poor, but it depends on the extent of liver involvement at diagnosis and on the presence or absence of extrahepatic dissemination. Historical data suggest that, with palliative care only, 20% to 30% of patients survive 3 years after detection of a single colorectal metastasis to the liver. Local therapies, such as surgical resection or physical ablation, usually are indicated only when there is no evidence of extrahepatic spread. The prognosis is somewhat better for the 10% to 30% of patients with liver metastasis who are eligible for surgery. Median survival was 24 to 42 months and survival at 5 years was 25% to 37% in retrospective series of patients resected for liver metastasis after complete excision of the primary tumor. Prognostic factors for recurrence after resection of hepatic metastasis include the presence of four or more lesions, tumor-free margins less than 1 cm, and elevated serum levels of carcinoembryonic antigen. Surgery is precluded for most patients with hepatic metastasis, either by the anatomic location, size, or number of lesions; by inadequate viable liver tissue that would remain after operation; or by comorbid conditions. Treatment options are limited for these patients. Percutaneous ethanol injection, used frequently outside the United States for hepatocellular carcinoma, appears less effective for liver metastasis, so is used infrequently. In the United States, most patients with inoperable liver metastasis are offered chemotherapy with fluorouracil or floxuridine, alone or with folinic acid (leucovorin). These drugs can be given systemically or by hepatic artery infusion and can be combined with other drugs such as doxorubicin, mitomycin, cisplatin, or, more recently, irinotecan or oxaliplatin. Chemotherapy may also be used as an adjunct to surgery when histology shows the margins are not free of tumor. Local ablative therapies using radiofrequency thermotherapy or cryosurgery have been introduced more recently. Transcatheter arterial chemoembolization (TACE), an older technique, has been used for patients with more extensive disease. But TACE is used more commonly for patients with primary hepatocellular carcinoma than for those with hepatic metastases, and substantially more data have been reported on outcomes of TACE for hepatocellular carcinoma than for hepatic metastases. This is a systematic review of evidence on the outcomes of radiofrequency ablation for treatment of inoperable liver metastases after complete excision of the primary tumor. Outcomes of interest are overall survival, diseaseor symptom-free survival, palliation, and adverse effects of treatment. Two uses of radiofrequency ablation are considered: used alone, and used in combination with resection or other therapies. Each is inNo competing interests declared.