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Surgery. 2016 Mar;159(3):901-7. doi: 10.1016/j.surg.2015.10.003. Epub 2015 Nov 14.

Is the 2-cm size cutoff relevant for small nonfunctioning pancreatic neuroendocrine tumors: A French multicenter study.

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Clinique de Chirurgie Digestive et Endocrinienne, Institut des Maladies de l'Appareil Digestif (IMAD), Hôtel Dieu, CHU de Nantes, Nantes, France. Electronic address:
Service de Chirurgie Générale et Digestive, Hôpital Purpan, CHU de Toulouse, Toulouse, France.
Clinique de Chirurgie Digestive et Endocrinienne, Institut des Maladies de l'Appareil Digestif (IMAD), Hôtel Dieu, CHU de Nantes, Nantes, France.
Service de Chirurgie Digestive et Endocrine, Hôpital Trousseau, CHU de Tours, Tours, France.
Service de Chirurgie Viscérale et Endocrinienne Hôpital de la Miletrie, CHU de Poitiers, Poitiers, France.
Service de Chirurgie Digestive, Générale et Endocrinienne, Hôpital Dupuytren, CHU de Limoges, Limoges, France.
Service de Chirurgie Digestive et Viscérale, Hôpital Hautepierre, CHU de Strasbourg, Strasbourg, France.
Service de Chirurgie Viscérale, Hôpital Larrey, CHU d'Angers, Angers, France.



Nonfunctioning pancreatic neuroendocrine tumors (NF-PNETs) are often discovered at a small size. No clear consensus exists on the management of NF-PNETs ≤ 2 cm. The aim of our study was to determine the prognostic value of indicators of malignancy in sporadic NF-PNETs ≤ 2 cm.


Eighty patients were evaluated retrospectively in 7 French University Hospital Centers. Patients were managed by operative resection (operative group [OG]) or observational follow-up (non-OG [NOG]). Pathologic characteristics and outcomes were analyzed.


Sixty-six patients (58% women) were in the OG (mean age, 59 years; 95% CI, 56.0-62.3; mean tumor size, 1.6 cm; 95% CI, 1.5-1.7); 14 (72% women, n = 10) were in the NOG (mean age, 63 years; 95% CI, 56-70; mean tumor size, 1.4 cm; 95% CI, 1.0-1.7). All PNETs were ranked using the European Neuroendocrine Tumor Society grading system. Fifteen patients (19%) had malignant tumors defined by node or liver metastasis (synchronous or metachronous). The median disease-free survival was different between malignant and nonmalignant PNETs, respectively: 16 (range, 4-72) versus 30 months (range, 1-156; P = .03). On a receiver operating characteristic (ROC) curve, tumor size had a significant impact on malignancy (area under the curve [AUC], 0.75; P = .03), but not Ki-67 (AUC, 0.59; P = .31). A tumor size cutoff was found on the ROC curve at 1.7 cm (odd ratio, 10.8; 95% CI; 2.2-53.2; P = .003) with a sensitivity of 92% and a specificity of 75% to predict malignancy.


Based on our retrospective study, the cutoff of 2 cm of malignancy used for small NF-PNETs could be decreased to 1.7 cm to select patients more accurately.

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