title: Surveillance and comparison of surgical prognosis for asymptomatic and symptomatic non-functioning pancreatic neuroendocrine tumors.
abstract: BACKGROUND
  The treatment of non-functioning pancreatic neuroendocrine tumors (NF-PNETs) still remains controversial. It is uncertain whether asymptomatic patients have better prognosis than symptomatic patients and whether surgery is necessary for asymptomatic patients.
  
  
  METHODS
  Patients with NF-PNETs who were managed surgically or by surveillance between June 2007 and December 2013 were retrospectively studied. The choice of surgery or surveillance was based entirely on the patient's desire. Survival prognosis was compared between asymptomatic and symptomatic patients, and evaluated among patients who were under surveillance.
  
  
  RESULTS
  Of the 53 patients with NF-PNETs, 48 (90%) were treated surgically. 25 patients (47%) were symptomatic patients, 23 (43%) asymptomatic, and five (10%) detected by surveillance. Among the latter group, one patient suffered from tumor progression and four had stable disease. When compared with symptomatic NF-PNETs, asymptomatic NF-PNETs showed lower pathology grades (P = 0.006), better 3-year cumulative progression-free survival and overall survival after surgical treatment. Parenchyma-preserving resection was associated with a higher risk of pancreatic fistula (71 vs. 17%, P = 0.007). A positive lymph node status (P = 0.003) and perineural or vascular invasion (P = 0.01) were significant predictors of tumor recurrence or metastasis. Patients with grade G3 disease (P = 0.005) or a tumor size >4 cm (P = 0.019) had poor prognosis.
  
  
  CONCLUSIONS
  Compared with symptomatic NF-PNETs, asymptomatic NF-PNETs had a lower degree of malignancy and better prognosis. Surveillance for small asymptomatic NF-PNETs needs to be further studied.
authors.affiliation: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery First Affiliated Hospital, School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, 310003, China.
authors.forename: Wenhao
authors.initials: W
authors.lastname: Ge
authors.affiliation: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery First Affiliated Hospital, School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, 310003, China.
authors.forename: Dongkai
authors.initials: D
authors.lastname: Zhou
authors.affiliation: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery First Affiliated Hospital, School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, 310003, China.
authors.forename: Shaoyan
authors.initials: S
authors.lastname: Xu
authors.affiliation: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery First Affiliated Hospital, School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, 310003, China; Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, 79 Qingchun Road, Hangzhou, 310003, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, 79 Qingchun Road, Hangzhou, 310003, China. Electronic address: wam@zju.edu.cn.
authors.forename: Weilin
authors.initials: W
authors.lastname: Wang
authors.affiliation: Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery First Affiliated Hospital, School of Medicine, Zhejiang University, 79 Qingchun Road, Hangzhou, 310003, China; Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, 79 Qingchun Road, Hangzhou, 310003, China; Collaborative Innovation Center for Diagnosis and Treatment of Infectious Disease, 79 Qingchun Road, Hangzhou, 310003, China. Electronic address: shusenzheng@zju.edu.cn.
authors.forename: Shusen
authors.initials: S
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000368:Aged; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018358:Neuroendocrine Tumors / Q000473:pathology / Q000601:surgery*; D010180:Pancreatectomy / Q000706:statistics & numerical data*; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000601:surgery*; D011379:Prognosis; D012189:Retrospective Studies; D018571:Sentinel Surveillance; D016896:Treatment Outcome
keywords: Pancreatic neuroendocrine tumors; Parenchyma-preserving resection; Surveillance; Survival