The cutoff of 2 cm of malignancy used for small nonfunctioning pancreatic neuroendocrine tumors (NF-PNETs) could be reduced to 1.7 cm to select patients more accurately, a new study published in the journal Surgery has shown.1

Because there is no clear consensus on the management of NF-PNETs 2 cm or smaller, researchers sought to determine the prognostic value of indicators of malignancy in sporadic NF-PNETs of that size.

Researchers retrospectively analyzed data from 80 patients treated at 7 French University Hospital Centers who were managed by operative resection or observational follow-up. All PNETs were ranked using the European Neuroendocrine Tumor Society grading system and a total of 15 patients had malignant tumor as defined by node or live metastasis.

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Results showed that the median disease-free survival was 16 months for malignant PNETs and 30 months for nonmalignant PNETs. Researchers found that tumor size had a significant impact on malignancy. Specifically, a tumor size cutoff of 1.7 cm was found to predict malignancy with 92% sensitivity and 75% specificity.

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PNETs form in islet cells of the pancreas and may be functioning or nonfunctioning, meaning that they either produce extra hormones or they do not. Most PNETs are functional tumors but most nonfunctional PNETs are malignant.2


  1. Regenet N, Carrere N, Boulanger G, et al. Is the 2-cm size cutoff relevant for small nonfunctioning pancreatic neuroendocrine tumors: A French multicenter study [published online ahead of print November 14, 2015]. Surgery. doi: 10.1016/j.surg.2015.10.003.
  2. Pancreatic Neuroendocrine Tumors (Islet Cell Tumors) Treatment (PDQ®). National Cancer Institute website. Updated July 30, 2015. Accessed November 19, 2015.