Analysis of clinicopathological characteristics and prognosis of appendiceal neuroendocrine tumors: a retrospective cohort study based on the SEER database.

Background: Appendiceal neuroendocrine tumors (ANETs) are rare, and there is a pressing clinical need for population-level data on their clinicopathological characteristics and prognosis to guide clinical decision-making. This study aimed to investigate the clinicopathological features and prognostic outcomes of patients with ANETs using the Surveillance, Epidemiology, and End Results (SEER) database.

Methods: We included patients diagnosed with ANETs from 2000 to 2020. Participant inclusion was based on confirmed ANET diagnosis in the SEER database. Clinical factors, including tumor grade, stage, surgical status, and patient demographics, were assessed. Patients were followed up through the SEER database to record survival outcomes. The Kaplan-Meier method and Cox proportional hazards models were employed to evaluate overall survival (OS) and cancer-specific survival (CSS).

Results: A total of 4,870 patients were enrolled, with females accounting for 61.3%. The median age was 40 years. Most patients presented with well-differentiated tumors (89.4%) and T1 stage disease (86.0%). Lymph node (4.6%) and distant (1.0%) metastases were rare. Surgical intervention was performed on 99.2% of patients. The 5-year OS and CSS rates were 92.8% and 97.2%. Multivariate Cox analysis revealed age [hazard ratio (HR) =10.05, P<0.001], female sex (compared to male, HR =0.70, P=0.004), and M stage (HR =2.35, P=0.01) as predictors of OS, while age (HR =10.12, P<0.001), poorly differentiated grade (HR =4.64, P=0.008), undifferentiated grade (HR =8.99, P=0.02), female sex (compared to male, HR =0.57, P=0.005), T4 stage (HR =3.24, P=0.01), and M stage (HR =5.44, P<0.001) were associated with CSS. After propensity score matching (PSM), males still exhibited significantly worse OS and CSS than females (P=0.003), and elderly patients had poorer OS and CSS compared to younger patients (P<0.001). However, among elderly patients, no significant differences in OS or CSS were observed between partial colectomy (PC) and subtotal colectomy (SC) groups (P=0.36 and P=0.07, respectively).

Conclusions: ANETs patients generally present with early-stage disease and favorable prognosis. However, the males and the elders tend to have worse prognosis than their female and younger counterparts. These findings suggest that closer monitoring and potentially more aggressive treatment strategies may be warranted for these high-risk groups. For elderly patients, PC may be a more favorable surgical option, balancing efficacy and morbidity.