Observation versus Resection for Small Asymptomatic Pancreatic Neuroendocrine Tumors: A Matched Case–Control Study

Abstract

Objective To analyze the natural history of small asymptomatic pancreatic neuroendocrine tumors (PanNET) and to present a matched comparison between groups who underwent either initial observation or resection. Management approach for small PanNET is uncertain. Methods Incidentally discovered, sporadic, small (<3 cm), stage I–II PanNET were analyzed retrospectively between 1993 and 2013. Diagnosis was determined either by pathology or imaging characteristics. Intention-to-treat analysis was applied. Results A total of 464 patients were reviewed. Observation was recommended for 104 patients (observation group), and these patients were matched to 77 patients in the resection group based on tumor size at initial imaging. The observation group was significantly older (median 63 vs. 59 years, p = 0.04) and tended towards shorter follow-up (44 vs. 57 months, p = 0.06). Within the observation group, 26 of the 104 patients (25 %) underwent subsequent tumor resection after a median observation interval of 30 months (range 7–135). At the time of last follow-up of the observation group, the median tumor size had not changed (1.2 cm, p = 0.7), and no patient had developed evidence of metastases. Within the resection group, low-grade (G1) pathology was recorded in 72 (95 %) tumors and 5 (6 %) developed a recurrence, which occurred after a median of 5.1 (range 2.9–8.1) years. No patient in either group died from disease. Death from other causes occurred in 11 of 181 (6 %) patients. Conclusions In this study, no patient who was initially observed developed metastases or died from disease after a median follow-up of 44 months. Observation for stable, small, incidentally discovered PanNET is reasonable in selected patients.

Duodenal neuroendocrine tumors: Somewhere between the pancreas and small bowel?

“…As a result, while early ENETS recommendations defined surgery as the only acceptable option for P‐NETs, most recent guidelines recommend watchful observation in selected patients who might not benefit from immediate intervention . Despite a 6% to 10% risk of nodal metastasis reported in most surgical series, updated ENETS guidelines suggest that observation is reasonable for small, <2 cm tumors due to their excellent long‐term survival particularly when considering the known morbidity of pancreatic surgery . Conversely, given their established propensity for distant metastasis, an oncologic resection is recommended for P‐NETs ≥ 2 cm and operative approach spans enucleation with formal lymphadenectomy to anatomic resection (AR) including pancreaticoduodenectomy or distal pancreatectomy …”

The Evolution of Neuroendocrine Tumor Treatment Reflected by ENETS Guidelines

“…But while surgery can always be considered, current guidelines also define selected patients who might not need immediate treatment and just have to be observed according to a well-defined watchful waiting protocol. Observation seems reasonable in pancreatic NETs smaller than 2 cm; however, follow-up was only limited to 3 or 4 years in these studies [40, 41]. Importantly, these recommendations are based on studies in patients with inherited tumor syndromes, like von Hippel Lindau disease, or MEN-1.…”

Role of surgery in pancreatic neuroendocrine tumor

“…After years of clinical and 1 year of radiological follow up, 82% of patients under active surveillance did not find any change in size of tumor. Sadot et al reported a case-matched comparative study between observation and surgery on patients with treatment naive PNET ≤3 cm (16). While patients in observation was older and tended to be shorter in follow up (44 vs. 57 months, P=0.06), median size did not change and no patients in either group was died from the disease at the end of study.…”

“…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.…”