P1.084: Treatment Trends and Outcomes in Pediatric Appendiceal Carcinoma within the National Cancer Database

Background: Appendiceal carcinoid tumor is a rare malignancy, most often discovered incidentally following appendectomy. While there are established treatment guidelines for adults, no standardized recommendations exist for pediatric patients. This study aimed to characterize the demographics, tumor features, treatment strategies, and survival outcomes of pediatric patients with appendiceal carcinoid tumors using a large national database.

Methods: We performed a retrospective cohort study using data from the National Cancer Database (NCDB). Patients with appendiceal carcinoid tumors were identified by ICD-O-3 topography code C18.1 and histology codes 8240–8249 (carcinoid, neuroendocrine tumors, and subtypes). Patients were stratified into three age groups: Pediatric (PEDS, ≤21 years), Young Adult (YA, 22–50 years), and Older Adult (OA, >50 years). Only cases with specified pathological stage (pT1–pT4) and complete survival data were included. We analyzed demographic characteristics, tumor features, treatment modalities, and overall survival using Chi-square tests, Kaplan-Meier survival analysis, and Cox proportional hazards models, with significance defined as p < 0.05.

Results: A total of 20,792 cases met inclusion criteria: 2,170 PEDS (10.4%), 8,391 YA (40.4%), and 10,231 OA (49.2%). Across all age groups, the tumors were more common in females (PEDS: 57.4%; YA: 60.9%; OA: 57.4%) and white individuals (PEDS: 87.9%; YA: 85.2%; OA: 89.0%).

Pediatric patients presented more frequently with early-stage disease. Among PEDS cases, 77.5% were classified as pT1, compared to 60.6% in YA and 40.6% in OA (p < 0.001). Higher-stage disease (pT3/pT4) was more common in adults. Lympho-vascular invasion was also less frequent in PEDS (8.8%) than in YA (11.0%) or OA (16.7%).

Surgery was the primary treatment in nearly all patients (PEDS: 99.9%; YA: 99.9%; OA: 99.8%), though the extent varied by age. Segmental resection was most common in PEDS (55.6%), whereas OA patients more frequently underwent subtotal colectomy or hemicolectomy (38.6% vs. 10.4% in PEDS). Adjuvant therapy was used more frequently in adults.

Pediatric patients had the highest overall survival at 1, 2, 5, and 10 years across all tumor stages. Stage pT4 disease was associated with the lowest survival in all groups. Similarly, poorly differentiated tumors were linked to worse outcomes, regardless of age

Conclusion: Pediatric patients with appendiceal carcinoid tumors tend to present with earlier-stage disease, lower histologic grade, and less lympho-vascular invasion compared to adults. They are typically treated with less aggressive surgery and rarely receive adjuvant therapy yet experience superior survival outcomes. These findings support the need for pediatric-specific, evidence-based treatment guidelines.