The Risk Factors for Metastasis in Non-Ampullary Duodenal Neuroendocrine Tumors Measuring 20 mm or Less in Diameter

Waku Hatta, Tomoyuki Koike, Katsunori Iijima, Kiyotaka Asanuma, Naoki Asano, Hiroaki Musha, Yoshifumi Inomata, Toshikazu Sano, Hiroyuki Endo, Atsushi Ikehata, Toru Horii, Motoki Ohyauchi, Satoshi Yokosawa, Atsuko Kasajima, Fumiyoshi Fujishima, Hironobu Sasano, Naoki Nakaya, Tomohiro Nakamura, Tooru Shimosegawa

Research output: Contribution to journalArticlepeer-review

29 Citations (Scopus)


Background/Aims: The treatment strategy for non-ampullary duodenal neuroendocrine tumors (NAD-NETs) ≤20 mm in diameter has not been established. In this study, we aimed to evaluate the detailed characteristics of NAD-NETs ≤20 mm in diameter to clarify the risk factors of subsequent metastasis. Methods: The patients with NAD-NETs ≤20 mm in diameter who had been treated at 12 institutions between 1992 and 2013 were enrolled. Clinical records were retrieved, and histopathological findings of all cases were centrally reviewed by 2 pathologists. Results: We studied 49 patients with a mean follow-up period of 66.5 months. Thirty-five patients were initially treated with endoscopic resection (ER), and 14 with surgery. A univariate analysis revealed the ORs and 95% CIs of the risk factors for metastasis were lymphovascular invasion (12.5 [2.01-77.9]), multiple tumors (9.75 [1.46-65.4]), a tumor size of 11-20 mm (6.67 [1.21-36.6]), and World Health Organization grade G2 (7.13 [1.16-43.9]). Five-year overall and disease-specific survival rates were 86.1 and 97.2%, respectively. Conclusion: This is the first study to demonstrate the risk factors of metastasis in NAD-NETs ≤20 mm in diameter. These findings may be helpful for determining the appropriate therapeutic approach and the clinical strategy of treatment following ER.

Original languageEnglish
Pages (from-to)201-209
Number of pages9
Issue number3
Publication statusPublished - 2017 Apr 1


  • Duodenum
  • Metastasis
  • Neuroendocrine tumor


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