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Is Multifocality an Indicator of Aggressive Behavior in Small Bowel Neuroendocrine Tumors?

Choi, Allen B. BS*; Maxwell, Jessica E. MD*; Keck, Kendall J. MD*; Bellizzi, Andrew J. MD; Dillon, Joseph S. MD; O'Dorisio, Thomas M. MD; Howe, James R. MD*

doi: 10.1097/MPA.0000000000000911
Original Articles

Objectives Many patients with small bowel neuroendocrine tumors (SBNETs) have multifocal tumors (MFTs), but the frequency of MFTs has varied widely across SBNET studies. It is also unclear whether patients with MFTs have more advanced disease or worse clinical course than do those with unifocal SBNETs. We set out to determine the frequency of multifocal and unifocal SBNETs and compare clinicopathologic factors, somatostatin receptor 2 expression, and survival.

Methods Clinicopathologic variables from 179 patients with surgically managed SBNETs were collected. Statistical comparisons were made using Welch t-test, Wilcoxon test, and Fisher’s exact test. Survival was assessed using the Kaplan-Meier method. Somatostatin receptor 2 expression was analyzed by quantitative polymerase chain reaction, and Ki-67 expression by immunohistochemistry.

Results Multifocal tumors were found in 45% of patients with SBNETs. Clinicopathologic factors such as grade, TNM stage, presence of distant metastases, mean somatostatin receptor 2 expression, success of imaging modalities, and preoperative and postoperative hormone levels were not significantly different between multifocal and unifocal groups. Progression-free survival and overall survival were also not significantly affected by multifocality.

Conclusions Clinicopathologic features and survival of patients with MFTs and unifocal tumors are remarkably similar. Although the etiology of MFTs is unclear, patients with MFTs do not have a more aggressive clinical course than patients with unifocal SBNETs.

From the Departments of *General Surgery, †Pathology, and ‡Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA.

Received for publication February 6, 2017; accepted August 3, 2017.

Address correspondence to: James R. Howe, MD, 4644 JCP, 200 Hawkins Dr, University of Iowa Hospitals and Clinics, Iowa City, IA 52240 (e-mail:

This study was supported by the Surgical Oncology grant T32 CA148062-01 (to J.E.M., K.J.K.), University of Iowa College of Medicine Summer Research fellowship (to A.B.C.), and Iowa NET SPORE 1 P50 CA174521-01 (to A.J.B., T.M.O., J.R.H.).

A.B.C. and J.E.M. contributed equally to this work.

The authors declare no conflict of interest.

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