Surveillance strategy for small asymptomatic non-functional pancreatic neuroendocrine tumors – a systematic review and meta-analysis

Abstract

Expectant management of small asymptomatic, sporadic, NF-PNETs could be a reasonable option in highly selected patients. However, the level of evidence is low and longer follow-up is needed to identify patients could benefit from upfront surgery instead of expectant treatment.

Unmet Needs in Functional and Nonfunctional Pancreatic Neuroendocrine Neoplasms

“…This also relates to identifying the group of higher risk patients who might benefit by adjuvant treatments [32]. The recurrence rate after resection in patients with NF-PanNENs varies from 9 to 40% at 3 years and is affected by whether patients with hereditable PanNENs are included, the percentage of patients with higher grade tumors (G2, G3) included, the percentage of patients with tumors with invasion (vascular, neural, lymphatic), disease stage, and percentage of patients with larger tumors (> 2–3 cm) [20, 21, 25, 33-36]. This will be discussed in more detail below.…”

“…This recommendation is based on the findings that NF-PanNENs of this size are not associated with increased mortality in MEN1 patients, many do not grow or show aggressive behavior, and these patients cannot be completely cured of PanNENs, because they all have small, microscopic NF-PanNEN tumors throughout the gland and only 0–12% ever become symptomatic [5, 11, 12, 45-47]. Only recently is this approach being increasingly used in patients with sporadic, asymptomatic NF-PanNENs [19-21, 23, 48]. This recommendation is not without controversy, with some authors advocating surgery for all PanNENs, whereas others support the conclusion that small, asymptomatic PanNENs are good candidates for surveillance [19-21, 49-52].…”

“…Only recently is this approach being increasingly used in patients with sporadic, asymptomatic NF-PanNENs [19-21, 23, 48]. This recommendation is not without controversy, with some authors advocating surgery for all PanNENs, whereas others support the conclusion that small, asymptomatic PanNENs are good candidates for surveillance [19-21, 49-52]. …”

“…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

“…Five-year metastasis free survival was comparable between observation and resection (99% vs. 88%, P=0.08). Sallinen et al reported a meta-analysis on surveillance strategy for small asymptotic non-functional PNET (17). It included 9 articles with 344 patients with sporadic and 64 patients with MEN1 related non-functional PNET.…”