Adamantinoma: A SEER-based Epidemiological Analysis.

Adamantinoma (AD) is a rare bone cancer accounting for less than 0.1-0.5% of all primary bone tumors. No consensus guidelines exist for the treatment of this disease and long-term (twenty-year) survival has yet to be explored. The Surveillance, Epidemiology, and End Results (SEER) Program was queried for patients with a diagnosis of primary AD (ICD-O-3 code 9261/3). Demographic and treatment variables were analyzed via Fisher's Exact Test and 20-year overall survival (20y OS) was assessed via log-rank analysis. Seventy-four patients with AD were identified; median age was 20-24 years. Multivariate analysis demonstrated that patients < 25 years of age at diagnosis with AD had increased 20y OS compared to those > 24 years (HR = 0.28; p = 0.028), while no other variables influenced survival. Subanalysis demonstrated patients > 40 years saw decreased survival (46% [11%, 81%]) compared to those ≤ 40 years (96% [89%, 104%]; p = 0.005). Patients ≤ 40 years of age at diagnosis were more likely to have local disease (78% of all 49 local cases) and less likely to have distant disease (0% of two cases) compared to patients > 40 years (p = 0.017). Stratifying by surgical procedure, no difference in 20y OS was appreciated (p = 0.12). Younger age at diagnosis provides mortality benefit and increased proportion of localized disease for those diagnosed with AD. No other demographic or treatment variables were found to influence 20y OS. Population-based analysis of AD is limited both by disease rarity and incomplete coding within SEER.