Patterns of care and long-term survival in metastasizing ameloblastoma: An NCDB study.

Abstract

e18153 Background: Metastasizing ameloblastoma (MA) is diagnosed when a benign but aggressive ameloblastoma spreads to distant sites without malignant transformation, with metastases typically found in the lungs and lymph nodes. MA most commonly affects 40–50-year-old men, and although rare and histologically benign, conservative treatment—such as curettage or enucleation—often results in recurrent disease and associated health risks. Given the rarity of MA, population-level data remain limited, and evaluating demographic patterns using the National Cancer Database (NCDB) may improve understanding of its epidemiology. Methods: A retrospective cohort analysis was performed using patients with histologically confirmed MA (ICD-O-3 Code 9310) in the 2004–2020 NCDB. Demographic, clinical, and socioeconomic variables (sex, race, Hispanic origin, facility type and location, insurance status, income, year of diagnosis, primary tumor site, analytic stage group, and Charlson-Deyo score) were summarized with descriptive statistics. Trends in incidence were evaluated using regression analysis. Results: A total of 308 patients with MA were identified from 2004–2020, with a stable incidence over time (R²=0.03). Patients were predominantly male (61.7%), non-Hispanic (86.0%), and White (54.5%), with a notably high representation of Black patients (34.7%). Nearly half received care at academic centers (48.1%), and most lived in metropolitan areas (87.0%). Private insurance was the most common payer (51.9%). The mandible (C411) was the most frequent primary site (73.7%), and 47.7% presented with stage I disease. Most patients had a Charlson-Deyo score of 0 (87.3%). Surgery was the primary treatment (90.3%), with complete resection achieved in 67.5% of cases. Radiation was used in 9.1%, and chemotherapy in a small minority; hormone and immunotherapies were not utilized. Palliative care was uncommon (1.6%). The mean age at diagnosis was 48.1 years, and tumors measured 44.5 mm on average. Early mortality was low (1.1% at both 30 and 90 days), consistent with the tumor’s benign histopathology. Likewise, mean overall survival was 14.2 years, with two-, five-, and ten-year survival rates of 95.2%, 89.3%, and 80.7%, respectively. Conclusions: This study provides the first population-level analysis of MA using the NCDB, addressing a major gap in understanding this rare entity. Consistent with prior case reports, MA primarily affected middle-aged men and most often originated in the mandible. We also describe socioeconomic patterns, showing that patients frequently resided in metropolitan areas and received care at academic centers. Surgical resection remained the predominant treatment, with excellent long-term survival reflecting the tumor’s indolent biology. Further investigation is warranted to better define demographic and healthcare access factors influencing presentation and management in this rare disease.