Abstract

e23501 Background: Adamantinoma is a rare low-grade primary malignant bone tumor accounting for less than 1% of all malignant bone tumors. It largely presents in the tibia of young adults, is locally aggressive, and can metastasize. Definitive diagnosis is primarily established by histopathological examination. This rare tumor with uncertain histogenesis remains under-studied. Therefore, exploring trends in diagnoses may provide insight into its epidemiology. The National Cancer Database (NCDB) was examined to reveal the demographic factors in patients diagnosed with Adamantinoma. Methods: A retrospective cohort analysis utilizing the 2004–2020 NCDB included 206 patients with a histologically-confirmed diagnosis of adamantinoma (ICD-O-3 Code 9261). Demographic factors such as age, sex, race, Hispanic status, insurance status, facility type, distance from facility, and Charlson-Deyo score were analyzed via descriptive statistics. Trends in incidence were interpreted using regression analysis. Results: A total of 206 patients were identified in the NCDB with a confirmed diagnosis of adamantinoma of long bones between 2004-2020. Incidence remained relatively stable over this time period (R² = 0.009). The most common primary site of diagnosis were the long bones of lower limb and associative joints (97%). Most individuals (88%) had a Charlson-Deyo comorbidity score of 0. The majority of patients (66%) were classified as Stage 1 AJCC staging. Men were more likely to be diagnosed (56%) compared to women (44%). Most patients were White (78%) and non-Hispanic (85%). A higher percentage of patients were privately insured (67%) and lived in metropolitan areas (87%). Treatment facilities primarily were academic programs (74%). Almost all of the patients were treated surgically (92%) with the most common approach being lymph node dissection (61%) more so than local tumor excision or removal of adjacent organs. Following surgery, the patients observed had a very good prognosis, with a 99% ninety-day survival, a 93% five-year survival, and an 89% ten-year survival. Conclusions: Adamantinoma has a risk for recurrent and metastatic disease. This first NCDB analysis on adamantinoma’s demographics addresses a significant knowledge gap on this topic. The primary site of diagnosis were lower extremity long bones, most commonly treated with surgical intervention, and had a high survival rate which is consistent with earlier studies. The majority of patients included in this study tend to be White, non-Hispanic, and privately insured. This may suggest a demographic and socioeconomic factor that plays a part in diagnosis, prognosis, and treatment of individuals with adamantinoma. Future research should focus on the understanding of factors that impact the course of one’s health and the etiology of this rare pathology.