Impact of Extent of Surgery on Survival in Patients with Small Nonfunctional Pancreatic Neuroendocrine Tumors in the United States

Abstract

Background Nonfunctional pancreatic neuroendocrine tumors (PNETs) ≤2 cm have uncertain malignant potential, and optimal treatment remains unclear. Objectives of this study were to better understand their malignant potential, determine whether extent of surgery or lymph node dissection is associated with overall survival (OS), and identify other factors associated with OS. Methods Patients with nonfunctional PNETs ≤2 cm were identified from the National Cancer Data Base (1998 to 2011). Descriptive statistics were used for patient characteristics and surgical resection patterns. Five-year OS was estimated using Kaplan–Meier analyses across extent of surgery and compared using the log-rank test. Cox proportional regression modeling was used to test the association between survival and extent of surgery. Results A total of 1854 patients with nonfunctional PNETs ≤2 cm were included. From 1998 to 2011, these tumors increased three-fold as a proportion of all PNETs. Among tumors ≤0.5 cm, 33 % presented with regional lymph node metastases and 11 % with distant metastases. Five-year OS for patients not undergoing surgery was 27.6 % vs. 83.0 % for partial pancreatectomy, 72.3 % for pancreaticoduodenectomy, and 86.0 % for total pancreatectomy (p< 0.01). Multivariate analysis demonstrated no difference in OS based on type of surgery or the addition of regional lymphadenectomy (p = 0.16). Younger age and later year of diagnosis were independently associated with improved survival. Conclusions Small nonfunctional PNETs represent an increasing proportion of all PNETs and have a significant risk of malignancy. Survival is improving over time despite older age at diagnosis. Type of surgical resection and the addition of lymph node resection were not associated with OS.

Unmet Needs in Functional and Nonfunctional Pancreatic Neuroendocrine Neoplasms

“…At present there are limited tools which identify which of the small, asymptomatic PanNENs will grow, and therefore the approach generally used is to serial image this tumor [19-21, 49-51]. There also is not complete agreement on what imaging modality should be used.…”

Role of surgery in pancreatic neuroendocrine tumor

“…The treatment decision was based on patients' age, pre-morbid conditions and patients' decision. It was reflected by the fact that patients in observation were usually older (13,16 [1998][1999][2000][2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011] and number of patients (1,854 patients) were retrieved from NCDB (24). To evaluate the effect of pancreatectomy, they included non-functional PNETs and non-specific neuroendocrine tumours.…”

Nowotwory neuroendokrynne trzustki — zasady diagnostyki i leczenia (rekomendowane przez Polską Sieć Guzów Neuroendokrynych)

“…Some studies have assessed the safety and possibility of the non-operative treatment of asymptomatic, sporadic NF-PNETs ≤ 2 cm in diameter, particularly in cases which would otherwise require extensive resections [11,[155][156][157]] (*evidence level 3). According to most authors, a conservative approach seems to be a safe option because most of the observed tumours did not reveal any significant changes in the follow-up period [155,158] (*evidence level 3).…”

“…According to most authors, a conservative approach seems to be a safe option because most of the observed tumours did not reveal any significant changes in the follow-up period [155,158] (*evidence level 3). However, some studies demonstrated that tumours < 2 cm may invade the lymph nodes and can be associated with distant metastases [157,[159][160][161][162][163] (*evidence level 3). According to some authors, a change in the size of tumours, which can be safely left for observation, should be considered, from ≤ 2 cm to ≤ 1.5-1.7 cm [160,162] (*evidence level 3).…”