The clinicopathologic and operative characteristics of patients with small nonfunctioning pancreatic neuroendocrine tumors

Abstract

Background Incidentally detected, small nonfunctioning pancreatic neuroendocrine tumors (NF‐PNETs) are increasingly diagnosed on imaging modalities. This retrospective investigation evaluated the clinicopathologic characteristics and perioperative and oncologic outcomes in patients with small NF‐PNETs undergoing curative resection. Methods The medical records of 444 patients who underwent pancreatic resection for NF‐PNETs at a single, large‐volume institution between January 2000 and December 2018 were retrospectively reviewed. Patients were divided into those with small (≤2 cm) and large (>2 cm) tumors based on the largest tumor diameter on preoperative computed tomography (CT). Outcomes were also evaluated in subgroups of patients with small NF‐PNET who did and did not undergo lymphadenectomy. Results Of the 444 patients with NF‐PNETs, 195 (43.9%) had small (≤2 cm) and 249 (56.1%) had large (>2 cm) NF‐PNETs. The rate of parenchyma‐preserving surgery (14.4% vs. 7.2%, p = 0.014) and the ratio of spleen preservation for left‐sided pancreatectomy (65.6% vs. 38.3%, p < 0.001) were higher in the small NF‐PNET group. Size on CT >2 cm (p < 0.001, hazard ratio [HR]: 5.836, 95% confidence interval [CI]: 2.474–13.769), presence of perineural invasion (p < 0.001, HR: 3.025, 95% CI: 1.640–5.577), World Health Organization (WHO) Grade 2 (p = 0.007, HR: 2.861, 95% CI: 1.325–6.176), and WHO Grade 3 (p < 0.001, HR: 11.537, 95% CI: 5.282–25.199) were independent predictors of disease‐free survival (DFS). DFS did not differ significantly in patients with small NF‐PNETs who did and did not undergo lymphadenectomy (p = 0.886). Conclusions Assessment of long‐term oncologic outcomes suggests that surgical resection may cure small NF‐PNETs. Minimally invasive surgery and organ‐preserving surgery are acceptable treatment options for select patients with small NF‐PNETs. The effect on survival outcomes of lymph node dissection for small NF‐PNETs remains unclear.

Prognostic Factors of Small Non-Functional Pancreatic Neuroendocrine Tumors and the Risk of Lymph Node Metastasis: A Population-Level Study

“…The reported incidence of LNM in small NF-PNETs varies from 2.6% to 27.5% ( 13 – 15 , 22 , 23 ). In our data, after the exclusion of patients with distant metastasis, the incidence of LNM was 9.9% in 751 patients with at least one examined lymph node.…”