Surgical Management of Hepatic Metastases

Hepatic metastases occur in about 85% of patients with small intestine NETs within 10 to 20 years. Primary small bowel NETs are most likely to metastasize to the liver (Figure 18-8), followed by primary tumors usually located in the pancreas, rectum, or lung.57 Patients with liver metastases are mainly considered for medical therapy because resection of these metastases is possible in only 10% of cases.59,66 The ideal intervention is a safe procedure (with minimal mortality [< 3%] and low morbidity [< 20%], avoiding specific complications such as hemorrhage, liver failure, or bile leakage) performed for a functional syndrome not amenable by medical treatment.66 However, the tumor mass must be reduced to 10 to 20% to control the symptoms when cytoreductive hepatic surgery is performed.57 Asymptomatic patients with resectable primary tumor but with liver masses unresponsive to nonsur-gical treatments are also good candidates.67 Recently, new methods have been recommended to treat hepatic metastases from NETs: (1) hepatic resection in two stages for diffuse metastasis and (2) local tumor destruction (eg, radiofrequency, cryotherapy, or laser ablation).67 The long-term survival benefit of these interventions is not yet known. The aim of hepatic metastases resection is to increase the overall survival and to provide effective, prompt, and long-term relief of symptoms (in about 90% of cases).12,67 The overall postoperative survival in patients with resected liver metastases at 5 years is about 47%. In a recent study of 31 patients, this survival rate was 86% in patients with R0 resection (curative surgery) versus 26% in patients with R2 resection (surgery leaving macroscopic remnants).57 The survival of patients with hepatic metastases is strongly influenced by the degree of differentiation of the primary tumor (5-year survival ranging from 70% for well-differentiated NETs to 17% for poorly differentiated lesions) and by the location of the primary tumor (5-year survival rate of 0% in patients with metastases of pancreatic origin).6,57,66

Because the progression of disease in patients with liver metastases from midgut carcinoid tumors is usually slow, some patients may be considered candidates for liver transplantation.59 The role of liver transplantation in the treatment of metastatic carcinoid tumors is still unclear.12 The rather unsatisfactory results of liver transplantation in the treatment of unresectable malignant liver tumors, together with a shortage of donor organs, make careful patient selection mandatory.57 Overall, the 5-year and disease-free survival rates are 47% and 24%,

Figure 18-8. Computed tomographic scan showing liver metastases from a primary small bowel neuroendocrine tumor.

respectively. However, patients with NETs and liver metastases have a significantly better prognosis than do patients with other tumors and hepatic metastases (69% versus 36% at 5 years).68

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