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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

  • Endocrine Tumors
  • Published:
Annals of Surgical Oncology Aims and scope Submit manuscript

Abstract

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.

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Acknowledgment

The authors express sincere gratitude to Marco Ricciardiello, MD for the assistance in systematic review and Donatella Santini, MD for the help with the study conception.

Disclosure

The authors declare that they have no conflict of interest and ethical adherence.

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Authors and Affiliations

  1. Department of Internal Medicine and Surgery (DIMEC), Chirurgia Generale-Minni, Alma Mater Studiorum-Università di Bologna, Bologna, Italy

    Claudio Ricci MD, Riccardo Casadei MD, Giovanni Taffurelli MD, Carlo Alberto Pacilio MD, Davide Campana MD & Francesco Minni MD

  2. Department of Specialized Diagnostic and Experimental Medicine (DIMES), Bologna, Italy

    Valentina Ambrosini MD & Santini Donatella MD

Authors
  1. Claudio Ricci MD
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  2. Riccardo Casadei MD
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  3. Giovanni Taffurelli MD
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  4. Carlo Alberto Pacilio MD
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  5. Davide Campana MD
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  6. Valentina Ambrosini MD
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  7. Santini Donatella MD
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  8. Francesco Minni MD
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Corresponding author

Correspondence to Claudio Ricci MD.

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Ricci, C., Casadei, R., Taffurelli, G. et al. 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. Ann Surg Oncol 24, 2603–2610 (2017). https://doi.org/10.1245/s10434-017-5946-8

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  • DOI: https://doi.org/10.1245/s10434-017-5946-8

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