Supplementary Material for: Meta-Analysis of Prognostic Factors for Recurrence of Resected Well-Differentiated Pancreatic Neuroendocrine Tumors

<b><i>Introduction:</i></b> Well-differentiated pancreatic neuroendocrine tumors (WDPNETs) are a group of rare and heterogeneous tumors. However, the prognostic factors for recurrence after curative resection still remain controversial. We aim to illustrate the prognostic factors for recurrence of resected WDPNETs. <b><i>Methods:</i></b> All relevant articles published through June 2020 were identified via PubMed, Embase, Web of Science, and Cochrane Library. Articles that examined the prognostic factors of WDPNETs were enrolled. <b><i>Results:</i></b> Ten articles were finally included in this study. From 1993 to 2018, 2,863 patients underwent curative resection and 358 patients had recurrence, and the combined recurrence rate was 13%. Furthermore, the pooled data indicated that patients with G2, positive lymph node and surgical resection margin, vascular invasion, and perineural invasion had a decreased disease-free survival for WDPNETs. However, gender, function, and tumor size had no significant relationship with WDPNETs recurrence. <b><i>Conclusion:</i></b> These findings demonstrated that G2, positive lymph node and surgical resection margin, vascular invasion, and perineural invasion could be prognostic factors for recurrence of resected WDPNETs, indicating that patients with these high-risk factors need closer postoperative follow-up and may benefit from adjuvant therapy.