Adenoid basal carcinoma: An NCDB study of demographic and socioeconomic factors.

e21550 Background: Adenoid basal carcinoma (ABC) is a rare, indolent variant of basal cell carcinoma that often presents as a pruritic, hemorrhagic lesion. Because the literature consists largely of isolated case reports and small series, its epidemiologic features remain poorly defined. Broader population-level data are needed to better understand its clinical context and diagnostic patterns. To address this gap, the National Cancer Database (NCDB) was analyzed to characterize the demographic and socioeconomic profile of patients diagnosed with ABC. Methods: A retrospective cohort analysis of the 2004–2020 NCDB identified patients with microscopically confirmed ABC (ICD-O-3 code 8098; N=237). Demographic variables, including sex, race, ethnicity, insurance status, facility type, and Charlson–Deyo score, were analyzed using descriptive statistics, and incidence trends were evaluated with regression analysis. Additional variables included treatment modalities, anatomical sites, and survival trends. Results: A total of 237 ABC cases were identified, with stable incidence from 2004–2020 (R²=0.0081). All patients were female, and a majority were White (65%), followed by Black (22.4%), and other races (12.7%). The mean age at diagnosis was 65.2 ± 13.8 years (range, 19–90), and most individuals were non-Hispanic (82%), lived in metropolitan counties with populations >1 million (65.4%), and had Charlson–Deyo scores of 0 (80.2%). Medicare (44.3%) and private insurance (36.3%) were the most common types of coverage. Treatment was concentrated in academic/research (42.6%) centers and comprehensive community cancer programs (28.3%). The most frequent primary site was the cervix uteri (177 cases, 74.7%), and the mean tumor size was 15.1 mm. Surgical management was performed in 92.0% of patients, with negative margins in 83.1%. Radiation (13.1%) and chemotherapy (6.3%) were used as secondary treatments in addition to surgery. Short-term mortality was low, with 99% 30-day survival and 97% 90-day survival. Mean survival was 160.3 months, with two-, five-, and ten-year survival rates of 96%, 90%, and 78%, respectively. Conclusions: This represents the first NCDB analysis of ABC, addressing a critical gap in its epidemiologic characterization. ABC predominantly affected older women and was commonly diagnosed among patients residing in metropolitan areas, with treatment frequently occurring at academic or research facilities. Most patients underwent surgery and exhibited favorable long- and short-term survival. Future studies should explore how demographic and socioeconomic factors influence diagnosis, treatment, and outcomes in this rare malignancy.