Pancreatic
neuroendocrine tumors (
pNETs) include functioning and non-functional
tumors. Functioning
tumors consist of
tumors that produce a variety of
hormones and their clinical effects. Therefore, determinants of resection of
pNETs should be discussed for each group of
tumors. Less than 10% of
insulinomas are malignant, therefore more than 90% of the cases can be cured by surgical resection.
Lymphadenectomy is generally not necessary in
insulinoma operation. If preoperative localization of the
insulinoma is completed, enucleation from the pancreatic body or tail, and distal
pancreatectomy can be performed safely by laparoscopy. When preoperative localization of a sporadic
insulinoma is not confirmed, surgical exploration is needed. Intraoperative localization of a
tumor, intraoperative
insulin sampling and frozen section are required. The crucial purpose of surgical resection is to control inappropriate insulin secretion by removing all
insulinomas.
Gastrinomas are usually located in the duodenum or pancreas, which secrete
gastrin and cause
Zollinger-Ellison syndrome (ZES). Duodenal
gastrinomas are usually small, therefore they are not seen on preoperative imaging studies or endoscopic ultrasound, and can be found only at surgery if a duodenotomy is performed. In addition,
lymph node metastasis is found in 40-60% of cases. Therefore, the experienced surgeons should direct operation for
gastrinomas. Surgical exploration with duodenotomy should be performed at a
laparotomy. Other functioning
pNETs can occur in the pancreas or in other locations. Curative resection is always recommended whenever possible after optimal symptomatic control of the clinical syndrome by medical treatment. Indications for surgery depend on clinical symptom control,
tumor size, location, extent,
malignancy and presence of
metastasis. A lot of non-functioning
pNETs are found incidentally according to the quality improvement of imaging techniques. Localized, small, malignant non-functioning
pNETs should be operated on aggressively, while in possibly benign
tumors smaller than 2 cm the surgical risk-benefit ratio should be carefully weighted. Surgical liver resection is generally proposed in curative intent to all patients with operable
metastases from G1 or G2
pNET. The benefits of surgical resection of liver
metastases have been demonstrated in terms of overall survival and quality of life. Complete resection is associated with better long-term survival.