SUN-266 Neuroendocrine Carcinoma: Survival Analysis and Mortality-to-incidence (MIR) ratio from SEER Database

Abstract Disclosure: S. Bajwa: None. H. Ali: None. U. Bajwa: None. A. Imran: None. F. Mohsin: None. F. Tuz Zahra: None. J. Santhi: None. R. Thirumaran: None. Background:Neuroendocrine Carcinomas (NC) are rare, high grade poorly differentiated tumors originating from neuroendocrine cells. These tumors have a relatively poorer prognosis than well differentiated neuroendocrine tumors, and factors like CD117 positivity or vascular invasion are associated with higher mortality. Data on Neuroendocrine carcinoma mortality and survival trends is limited; hence our purpose is to determine these trends from the latest data on SEER stat database. Methods: Data was collected from Surveillance, Epidemiology and End Result database Research Plus Data, 17 Registries, Nov 2023 Sub (2000-2021), using the ICD Code 8246/3 for neuroendocrine carcinoma. The analysis was stratified based on age, sex, race, year of diagnosis, stage, primary site labelled and various treatment modalities. Survival curves were compared using the Log-Rank test (GraphPad Prism).Results:Total 41353 cases of NC were extracted, of which 51.9% were males. The neoplasm was most seen in Caucasian (70.9%) followed by Black (11.5%), Hispanics (10.8%), Asians/Pacific Islanders (5.8%), Alaskans/American Indians (0.55%) and unknown race (0.5%). Median age of diagnosis was 66 years. 5-yearly Mortality-to-Incidence Ratio (MIR) was calculated as 90.3% for 2000-2005, 80.2% for 2006-2010, 67.5% for 2011-2015, and 57.9% for 2016-2021 (p <0.0001, Log-Rank test for trend). Overall median of survival (OS) was 16 months, with 1-year OS of 54% (CI 95%, 53.5%-54.5%), 3-year OS of 38.1% (CI 95%, 37.6%-38.6%), and 5-year OS of 32.1% (CI 95%, 31.6%-32.6%). The median of survival (MoS) was higher in younger age groups, with a progressive decline in survival with advancing age (p <0.0001). Survival calculated for males was 13 months and 20 for females (p <0.0001). While MoS was higher in Hispanics (21 months), followed by Blacks and Asians/PI (20), Caucasians (14) and Alaskans (12) (p <0.0001). MoS for stage was notable for localized (169 months), regional (60), distant (7), unknown stage (9) (p <0.0001). Anatomically, survival analysis revealed higher MoS for connective tissue (64 months), carotid/aortic body (61) and lowest in disease involving unknown primary site (6) and thoracic cavity (8) (p <0.0001). Treatment based survival revealed: surgery (55 months) vs no surgery (8) (p<0.0001), chemotherapy (11 months) vs no chemotherapy (28) (p <0.0001), XRT (12 months) vs No XRT (18) (p <0.0001).Conclusion:Neuroendocrine carcinoma is an aggressive neoplasm, more prevalent in males and Caucasians. Our study revealed a progressive decline in 5-year MIR from 2000 to 2021, likely attributable to earlier diagnosis and advancement in therapeutic modalities. Superior survival was associated with younger age, female sex, Hispanic race, localized tumor, disease primarily involving the connective tissue, and surgical management. Presentation: Sunday, July 13, 2025