title: Impact and Clinical Predictors of Lymph Node Metastases in Nonfunctional Pancreatic Neuroendocrine Tumors.
abstract: BACKGROUND
  The optimal surgical management of nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) is still controversial. Here, we evaluated the impact of lymph node status on postoperative recurrence in patients with NF-PNET and the potential of preoperative variables for predicting lymph node metastasis (LNM).
  
  
  METHODS
  In this mono-institutional retrospective cohort study conducted in 100 consecutive patients who underwent NF-PNET resection between January 2004 and December 2014, we evaluated risk factors for survival using the Kaplan-Meier method and the Cox regression model. Predictors of LNM were evaluated using the logistic regression model, and the power of predictive models was evaluated using receiver operating characteristic curve analysis.
  
  
  RESULTS
  Five-year disease-free survival of resected NF-PNET was 64.1%. LNM was independently associated with postoperative recurrence (hazard ratio = 3.995, P = 0.003). Multivariate analysis revealed tumor grade as an independent factor associated with LNM (G2 vs. G1: odds ratio [OR] =6.287, P = 0.008; G3 vs. G1: OR = 12.407, P = 0.001). When tumor grade was excluded, radiological tumor diameter >2.5 cm (OR = 5.430, P = 0.013) and presence of symptoms (OR = 3.366, P = 0.039) were significantly associated with LNM. Compared to neoplasms with radiological diameter >2.5 cm (32.1%), tumors ≤2.5 cm had an obviously lower risk of LNM (7.7%), indicating the reliability of this parameter in predicting LNM (area under the curve, 0.693). Incidentally discovered NF-PNETs ≤2.5 cm were associated with a low-risk of LNM and excellent survival.
  
  
  CONCLUSIONS
  LNM is significantly associated with postoperative recurrence. Radiological tumor diameter is a reliable predictor of LNM in NF-PNETs. Our results indicate that lymphadenectomy in small (≤2.5 cm) NF-PNETs is not routinely necessary.
authors.forename: Yu
authors.initials: Y
authors.lastname: Jiang
authors.forename: Jia-Bin
authors.initials: JB
authors.lastname: Jin
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhan
authors.forename: Xia-Xing
authors.initials: XX
authors.lastname: Deng
authors.affiliation: Department of General Surgery, Ruijin Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai 200025, China.
authors.forename: Bai-Yong
authors.initials: BY
authors.lastname: Shen
mesh_terms: D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010190:Pancreatic Neoplasms / Q000150:complications / Q000473:pathology* / Q000601:surgery; D016016:Proportional Hazards Models; D012189:Retrospective Studies