Mortality Risk in Mucinous Appendiceal Neoplasms: Insights from a National Database

We sought to identify mortality predictors among patients with mucinous appendiceal adenocarcinoma (MAA) and high-grade appendiceal mucinous neoplasm (HAMN). Cases of HAMN and MAA in the National Cancer Database years 2007-2021 were analyzed. Cox regression models identified mortality risk factors. Among 3,738 cases, 1.9% had HAMN, 49.1% low-grade MAA, 6.8% high-grade MAA, and 42.3% MAA grade unknown. Patients with HAMN often underwent partial colectomy, whereas patients with MAA more frequently received hemicolectomy or total colectomy. Chemotherapy was utilized in 4.4% HAMN, 54.0% low-grade MAA, 65.8% high-grade MAA, and 61.3% MAA grade unknown (p < 0.001). Patients with high-grade MAA had a greater risk of death than low-grade MAA (HR 2.04, 95%CI 1.71-2.44) but there was no difference in the risk of death between HAMN and low-grade MAA (HR 1.00, 95%CI 0.39-2.54). Surgery lowered mortality risk, while positive margins (HR 1.87, 95%CI 1.61-2.13) and lymphovascular invasion (LVI) (HR 2.01, 95%CI 1.66-2.45) increased it, and chemotherapy showed no effect (HR 0.91, 95%CI 0.80-1.04). Mortality risk is similar for HAMN and low-grade MAA. Key mortality predictors include age, sex, margins, and LVI. The minimal effect of chemotherapy highlights the crucial role of surgery in improving survival.