Surgery, Liver Directed Therapy and Peptide Receptor Radionuclide Therapy for Pancreatic Neuroendocrine Tumor Liver Metastases

SIMPLE SUMMARY: Pancreatic neuroendocrine tumors are tumors with varying degrees of aggressiveness. The most frequent site of metastasis is the liver. Treatment methods for pancreatic neuroendocrine tumor liver metastases (NETLM) range from medications to surgical resection. The aim of this article is to review the published literature on treatment of pancreatic NETLM using surgery, liver directed therapy (bland embolization, chemoembolization and radioembolization) and peptide receptor radionuclide therapy (PRRT). Surgical resection for patients with resectable disease is associated with the longest survival. Locoregional therapy and PRRT were once reserved for unresectable patients but are now used in increasingly creative ways in combination with surgery to improve symptoms and prolong survival. ABSTRACT: Pancreatic neuroendocrine tumors (PNETs) are described by the World Health Organization (WHO) classification by grade (1–3) and degree of differentiation. Grade 1 and 2; well differentiated PNETs are often characterized as relatively “indolent” tumors for which locoregional therapies have been shown to be effective for palliation of symptom control and prolongation of survival even in the setting of advanced disease. The treatment of liver metastases includes surgical and non-surgical modalities with varying degrees of invasiveness; efficacy; and risk. Most of these modalities have not been prospectively compared. This paper reviews literature that has been published on treatment of pancreatic neuroendocrine liver metastases using surgery; liver directed embolization and peptide receptor radionuclide therapy (PRRT). Surgery is associated with the longest survival in patients with resectable disease burden. Liver-directed (hepatic artery) therapies can sometimes convert patients with borderline disease into candidates for surgery. Among the three embolization modalities; the preponderance of data suggests chemoembolization offers superior radiographic response compared to bland embolization and radioembolization; but all have similar survival. PRRT was initially approved as salvage therapy in patients with advanced disease that was not amenable to resection or embolization; though the role of PRRT is evolving rapidly