Abstract
e12562 Background: Encapsulated papillary carcinoma (EPC) is a very rare form of breast cancer characterized by fibrous encapsulation and expansile growth, causing 1-2% of all cases. A summary of 25 case reports found that although two-thirds of cases had invasive growth, EPC responded well to local therapy and is considered a favorable diagnosis as a result. Because classification and diagnostic criteria for EPC continues to be debated, examination of the demographics could prove useful in determining trends. Methods: A retrospective cohort study done using data from the National Cancer Database (NCDB) from 2004–2020 found 314 patients with an EPC diagnosis through histology. The following demographics were considered: age, sex, race, Hispanic identity, distance from residence to treatment facility, insurance coverage, type of facility, and Charleson-Deyo score. These variables were then analyzed through descriptive statistics. Results: 314 patients were identified with a steadily increasing number of cases diagnosed per year until 2018, when cases per year dropped from 46 to 6 or below for the remaining 3 years (2018, 2019, 2020). Of these 314 patients, 16 were male and 298 were female. (5.1% and 94.9%, respectively). The average age of diagnosis was 69.6 years with a standard deviation of 11.8 and a range of 30 to > 90 years. The majority (99.7%) were found in the breast, with the remaining found in the endometrium. The majority of individuals (82.2%) had Charlson-Deyo comorbidity scores of 0. The majority of patients were non-Hispanic White, accounting for 88.9% of the total. A higher number of patients belonged to the highest income bracket, with 35.0% in the top quartile compared to those in other quartiles. The majority of patients had Medicare insurance, making up 63.1% of the total. More patients resided in counties with over 1 million people (56.7%) compared to those living in counties with a population below 1 million (43.3%). Most patients were treated at non-academic cancer centers (65.6%). On average, patients lived 19.8 miles (SD = 74.7, range = 1.8 – 370) from the treatment facility. Conclusions: Based on our literature review, this is the first NCDB analysis on EPC and thus addresses a significant knowledge gap on the topic. With an average age of diagnosis at 69.6 years, it is not surprising that the majority of patients were insured through Medicare. Male cases, while rare, support previous literature. Most commonly, EPC patients were most diagnosed in metropolitan areas. The majority of cases were diagnosed in the breast and most patients were treated at non-academic medical centers. While the vast majority of cases occurred in non-Hispanic white patients, it is unclear how much is due to race and how much is related to disparities in healthcare access and underdiagnosis in non-white races. Thus, further research is needed to understand which demographic factors prove to be the strongest predictors of EPC.