A Comparison Between Appendiceal and Nonappendiceal Neuroendocrine Tumors in Children and Young Adults

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.