Abstract
e18090 Background: Mixed medullary-follicular carcinoma (MMFC) is a rare malignant type of cancer that affects the thyroid. Unlike other thyroid cancers, MMFC is distinct by its solid-nonfollicular pattern which includes both follicular and C-cell elements. Nearly 70% of patients present with distant metastasis to the lungs, bone, brain and/or liver with a median survival time of 75 months, plus or minus 51 months. Because MMFC is a rare cancer, analyzing the trend in diagnoses can provide important information about its epidemiology. The National Cancer Database (NCDB) was analyzed to determine how patient demographic characteristics affected diagnosis of MMFC. Methods: A retrospective cohort study from 2004 to 2020 was conducted using the NCDB. 153 patients were found with a histologically confirmed diagnosis of MMFC (ICD-8346-3). Gender, race, Hispanic origin, level of education, insurance coverage, type of treatment facility, and distance from facility were analyzed via descriptive statistics and trends in incidence were interpreted using regression analysis. Results: The frequency of patients diagnosed with MMFC has remained consistent since 2004 (R 2 = 0.1) with over 10 diagnoses per year. Of the 153 patients found, the average age of diagnosis was 59.05 years (SD = 14.36, range = 18 – 90 years). Approximately two-thirds of patients were female (62.7%) and the remainder were male (37.3%). Most of the patients were Non-Hispanic White (86.3%) compared to 7.2% of the patients which were of Spanish-hispanic origin. More patients were in the top income quartile (37.3%) than those in the second (18.3%), third (21.6%), or fourth (11.1%) quartiles. The other 11.8% were of unknown income status. The majority of patients were privately insured (52.9%), followed by coverage under Medicare/Medicaid (43.1%). More patients lived in metropolitan counties with a population of 250,000 or more (88.2%) compared to urban or rural areas (11.8%). A large percentage of patients were treated at an academic or comprehensive community cancer program (72.6%) compared to non-academic programs (27.4%). Patients traveled an average of 33.9 miles (SD = 93.90, Range = 0.5 – 806.8) to get to the treatment facility. Conclusions: MMFC remains a rare diagnosis. This study explores a significant gap in existing knowledge on patient characteristics that might present with MMFC. The majority of patients were White, non-Hispanic, insured by private insurance, lived in metropolitan areas, and in the top quartile of income earners. This novel study of socioeconomic factors in MMFC patients suggest that patients diagnosed with this uncommon cancer might have better access to diagnosis. Previous literature on MMFC suggested a predilection for males, but our findings serve as contrary evidence for such preference. As such, additional research to comprehend the role that sex and socioeconomic status might have on MMFC would be valuable.