Evolving Patterns in the Detection and Outcomes of Pancreatic Neuroendocrine Neoplasms

Abstract

Objective: To assess changing patterns in the detection and outcomes of pancreatic neuroendocrine neoplasms (PNENs). Design: Retrospective review from May 21, 1977, through September 16, 2005. Setting: Massachusetts General Hospital, a tertiary care center. Patients: We evaluated 168 patients (51% male; mean age, 56 years) who underwent surgery for histologically confirmed PNENs. Main Outcome Measures: Surgical outcomes, survival, and changes in presentation of PNENs in 2 time groups: 1977-1999 (77 patients) and 2000-2005 (91 patients). Results: Ninety-eight patients (58.3%) had nonfunctioning PNENs, 86 of which were incidental. Insulinomas were the most common type of functional neoplasm (33.3%), followed by gastrinomas and glucagonomas; 12 patients (7.1%) had multiple endocrine neoplasia type 1. Of the neoplasms, 107 (63.7%) were located in the pancreatic body or tail. A pancreaticoduodenectomy was performed in 37 patients (22.0%), distal pancreatectomy was done in 88 (52.4%), and the rest had either middle segment pancreatectomy or enucleation. There were no operative deaths. We classified 76.8% of neoplasms as benign; of those classified as malignant, 25.6% had liver metastases. Of the patients, 10.1% received adjuvant therapy. Complete follow up was available in 90.5% of patients (mean, 63.3 months). Five- and 10-year actuarial survival rates were 77% and 62%, respectively. Incidentally discovered nonfunctioning neoplasms were significantly more frequent in the last 5 years (60.4% vs 40.3%; = .007), with a trend toward smaller neoplasms (mean, 4.2 cm vs 5.6 cm; = .19) and lesser likelihood of malignancy (21.8% vs 40.0%; = .08). Conclusions: We report a large single-center experience with PNENs. Increasing numbers of PNENs are being resected, largely owing to the incidental detection of nonfunctioning neoplasms. This may lead to the treatment of smaller and less malignant neoplasms. Pancreatic neuroendocrine neoplasms (PNENs) are rare entities with a wide spectrum of clinical presentation. The secretion of hormonal products into the blood results in functional neoplasms that cause clinical symptoms, and thus they are classified according to their hormonal product. In contrast, nonfunctional neoplasms do not secrete a hormonal product with a known clinical effect, and usually disease does not become apparent until they are large enough to cause impingement of adjacent structures with symptoms of jaundice, abdominal pain, or weight loss. Pancreatic neuroendocrine neoplasms differ both biologically and clinically from pancreatic adenocarcinoma. In comparison to pancreatic adenocarcinoma, in which the 5-year and 10-year actual survival rates in patients who have undergone resection remain very low (15% and 4%, respectively), most PNENs are reported to display an indolent course and are associated with longer survival. The natural history of PNENs is largely unknown. Although they are found in 0.5% to 1.5% of autopsies, they occur with an annual incidence of only about 5 to 10 cases per million persons, which is thought to reflect the asymptomatic nature of most of these neoplasms. Currently, complete surgical resection is thought to be the only curative treatment for PNENs. Our study aims to describe a large single-center experience with the operative management of PNENs, including analysis of clinical presentation, operative course, surgical morbidity, and long-term survival.