Sporadic Small (≤20 mm) Nonfunctioning Pancreatic Neuroendocrine Neoplasm: is the Risk of Malignancy Negligible When Adopting a More Conservative Strategy? A Systematic Review and Meta-analysis

• Published in: Annals of surgical oncology Vol. 24; no. 9; pp. 2603 - 2610
• Main Authors: Ricci, Claudio, Casadei, Riccardo, Taffurelli, Giovanni, Pacilio, Carlo Alberto, Campana, Davide, Ambrosini, Valentina, Donatella, Santini, Minni, Francesco
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2017; Springer Nature B.V
• Subjects: Conservative Treatment; Endocrine Tumors; Humans; Lymph; Lymph nodes; Lymphatic Metastasis; Malignancy; Medicine; Medicine & Public Health; Meta-analysis; Metastases; Metastasis; Neoplasm Invasiveness; Neoplasm Staging; Neuroendocrine tumors; Neuroendocrine Tumors - secondary; Neuroendocrine Tumors - surgery; Neuroendocrine Tumors - therapy; Oncology; Pancreas; Pancreatic cancer; Pancreatic Neoplasms - pathology; Pancreatic Neoplasms - surgery; Pancreatic Neoplasms - therapy; Risk Assessment; Surgery; Surgical Oncology; Survival Rate; Tumor Burden; Tumors; Lymph Nodal Metastases; European Neuroendocrine Tumor Society (ENETS); Microscopic Vascular Invasion; 2016 ENETS Guidelines; Nonfunctioning Pancreatic Neuroendocrine Tumors
• ISSN: 1068-9265; 1534-4681
• DOI: 10.1245/s10434-017-5946-8

Background The management of small (≤20 mm), nonfunctioning pancreatic neuroendocrine neoplasms (pNENs) remains under debate. The European Neuroendocrine Tumor Society guidelines advocate the possibility of a conservative approach. Methods A systematic literature search was conducted to identify all studies comparing the risk of malignancy in small pNENs with respect to large ones (>20 mm). Malignancy was defined based on the presence of nodal metastases. Distant metastases, tumor grading (G2–3), vascular microscopic invasion, stage III-IV, and overall and disease-free survival also were evaluated. The data were reported in two ways: using the risk difference (RD) and the likelihood of being helped or harmed (LHH). Results The search identified only 6 eligible studies with an overall population of 1697 resected pNENs: 382 (22.5%) small and 1315 (77.5%) large. The RD of lymph nodal metastases was −0.26 (95% confidence interval (CI): −0.31 to −0.22; P  < 0.001). The LHH was 0.34, suggesting that the risk of leaving a malignancy during follow-up due to the adoption of a conservative strategy was three times higher than the benefits. The risk difference of distant metastases, G3 lesions, G2–G3 lesions, stage III/IV, microscopic vascular invasion, death, and recurrence of the disease were lower in small NF-PNETs than large ones. The related LHH values suggested that a watch-and-wait policy never provided a benefit. Conclusions Even if the malignancy rate in sporadic, small pancreatic neuroendocrine neoplasms was lower than in large ones, this difference did not justify a watch-and-wait policy.