Pancreatic
neuroendocrine tumors (
PNETs) are rare, accounting for approximately 2% of primary malignant
tumors of the pancreas. Compared with common pancreatic ductal
adenocarcinomas, they grow more slowly, are less invasive and have a better prognosis. At present, surgery is the preferred method of treatment of
PNETs, and offers the only chance of a cure. However, owing to the occult onset of
PNETs, once diagnosed they are often inoperable when the diagnosis is established, and the optimal treatment of patients with inoperable liver
metastases remains uncertain. In recent years, targeted
drug therapies have emerged and have proved effective in prolonging progression-free survival in patients with advanced well-differentiated
PNETs, but hardly any progress has been made in the treatment of poorly differentiated
PNETs. In the patient described in this report, who had a poorly differentiated
PNET with multiple hepatic
metastases and had refused cytotoxic
chemotherapy, oral
sunitinib malate treatment for 22 months with regular follow-ups proved tolerable and effective in significantly reducing the size of the intrahepatic masses.