Hepatic surgery for metastases from neuroendocrine tumors

Cytoreductive therapy is effective in the management of metastatic neuroendocrine tumors to the liver, independent of their functioning status. In functioning tumors, clinical endocrinopathies are relieved in most patients and this response usually lasts for several months. Major morbidity and mortality are not greater than the average complication rate for resection for nonneuroendocrine metastatic tumors at major centers; therefore, surgical outcomes appear to justify operative intervention. Patients whose primary tumor can be controlled, whose metastases outside the liver are limited, and who have a reasonable performance status are candidates for resection. The authors' data support the previous statements. The current mortality rate of 1.2% and major morbidity rate of 15% clearly represent the success of the operative approach in such complex cases (54% of patients received a resection of at least one lobe) [9]. A symptomatic response in the 95% range with a median response of 45 months adds many months of symptom-free survival to the lives of most patients [9]. In the literature reviewed for this article, more than half of the patients also underwent a major hepatic resection and 40% of them had concurrent resection of the primary tumor. These data confirm that resection in selected patients is not more complicated or risky than resection for other metastatic tumors. Endocrinopathies have not increased anesthetic or operative risk in this population; however, these results are the product of managing these patients over time, becoming familiar with their clinical syndromes, and being active in the prevention of life-threatening endocrine complications (i.e., carcinoid crisis). The authors have learned over time that patients with valvular disease are not good candidates for surgery. These patients develop right-sided heart failure with an increase in the central venous pressure. This condition can result in massive hemorrhage during the liver resection because of the difficulty in controlling backbleeding from the hepatic veins [26]. Correction of valvular disease is warranted for safe liver resection. The authors' current policy is to rule out valvular disease in every patient with carcinoid tumors and repair the valves prior to hepatic resection when indicated [27]. This policy clearly has decreased the complication rate. Even though liver transplantation seems to be very attractive as a means of eradicating the disease, this has not been common in clinical practice because of the shortage of allografts, and the overall costs and complications of the procedure override its benefits, especially when compared with partial hepatectomy. Current methods to detect the spread of disease that were not readily available in the past, such as MRI and indium-111 pentetreotide (Octreoscan), may expand the applications of transplantation and allow for better selection of candidates. The option of transplantation is still open for improvement and is dependent on organ availability and better staging of the disease. Metastases from neuroendocrine tumors are hypervascular, favoring the application of MRI as the single imaging method; MRI not only evaluates the location and characteristics of the lesions but also determines the relationship with major vessels and bile ducts. Spiral CT scan has been used extensively in the past with acceptable results. Indium-111 pentetreotide functions on the base of somatostatin receptors present in these tumors, but its use has not been established definitely in the work-up of these patients. Perhaps the best use of indium-111 pentetreotide is in the evaluation of disease beyond the primary and liver locations, including bone metastases; its use therefore will likely affect the preoperative work-up of candidates for transplantation [28]. Once the patient has been deemed to have resectable disease by the preoperative work-up, several steps need to be completed prior to surgery to decrease the effect of specific endocrinopathies. For patients with symptoms related to carcinoid tumors, preoperative preparation with 150 to 500 micrograms of somatostatin decreases the chances of carcinoid crisis, which is manifested by hemodynamic instability [29]. The use of this medication intraoperatively should be kept in mind because a carcinoid crisis can occur despite anesthetic premedication. For islet cell tumors, treatment of underlying endocrinopathy has been initiated before referral for surgical treatment in most patients. Surgery is appropriate for patients with metastatic neuroendocrine tumors for the following two reasons: (1) many of them still have the primary tumor in place and resection should be undertaken to avoid acute complications and (2) the addition of adjunctive ablative therapies to surgical resection accomplishes the control of greater than or equal to 90% of the bulk of the tumor. If preoperative evaluation indicates that less than 90% of the tumor is treatable, surgical therapy is contraindicated. Last, even when complete resections are performed, the recurrence rate for these tumors is extremely high. In practical terms, patients with metastatic neuroendocrine tumors are seldom cured. The best hope physicians can offer these patients is an extended survival period with minimal endocrine symptoms and decreased requirements of somatostatin analogs.