A Comparison Between Appendiceal and Nonappendiceal Neuroendocrine Tumors in Children and Young Adults: A Single-institution Experience.

Background: Pediatric neuroendocrine tumors (NETs) are rare tumors. The purpose of this study is to report the clinical characteristics and outcomes of pediatric patients treated for NET at a single institution.
Procedure: A retrospective record review.
Results: There were 33 evaluable patients with median age of 17.9 years (range, 9.9 to 21.9 y) and predominantly females (58%). There were 17 patients with well-differentiated appendiceal NET, whereas 16 were nonappendiceal. Most common nonappendiceal sites were unknown primary (N=6) and pancreas (N=4). Majority of tumors were low grade (N=24, 73%) and small (T1, N=22, 67%). Nonappendiceal tumors were more likely to be larger or high-grade tumors (5/16, 31%), or with metastasis. All appendiceal NET patients underwent curative surgery. All patients who experienced treatment failure had nonappendiceal NET, despite prior chemotherapy in 8 of 9 patients. The 5-year overall survival rates for patients with appendiceal and nonappendiceal NET were 100% and 66% (95% CI, 45%-95%; P=0.006); and 5-year relapse-free survival rate for patients with appendiceal and nonappendiceal NET were 100% and 41% (95% CI, 22%-75%; P=0.002).
Conclusions: Well-differentiated appendiceal tumors were the most common pediatric NET and have an excellent prognosis. Better therapies are needed for patients with nonappendiceal NET.