Epidemiology of rectal and small intestinal carcinoids: Two distinct tumors?

Abstract

399 Background: Gastrointestinal carcinoids (GIC) are most commonly found in the small intestines. However, in this era of screening colonoscopy, the incidence of rectal carcinoids (RC) is increasing. The aim of this study was to determine if differences exist between the two most common carcinoid tumors. Methods: Small intestinal and rectal cancers were reviewed from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute from 2000-2007. Factors reviewed included age, gender, ethnicity, and survival. Results: 12,931 small intestinal cancer tumors included 4,731 (36.6%) small intestinal carcinoids (SIC). 57,850 rectal cancer tumors included 4,550 (7.9%) RC. Comparing RC and SIC, RC presented at a younger age (56.2 vs. 64.5 years, p<0.001). RC were more common among women (50.6 vs. 47.0%, p<0.001). The ethnic distribution of SIC and RC were significantly different. SIC were more common among Whites (W) (76.0 vs. 51.0%) while RC were more common among each ethnic minority group: Blacks (B) (19.9 vs. 14.3%), Hispanics (H) (13.0 vs. 6.5%), Asians (A) (14.9 vs. 2.7%), and American Indians/Alaskans (AI) (1.1 vs. 0.4%); p<0.001. RC were more common than SIC among women for every ethnic group (percentage of patients who are women W 48.1 vs. 46.8%, B 59.3 vs. 50.6%, H 50.3 vs. 44.3%, A 46.5 vs. 41.1%, AI 72.0 vs. 47.1%), although this reached significance in only Black females (p=0.001). Mean survival was better in RC (93.4 vs. 65.8 months, p<0.001) by Kaplan-Meir analysis. Conclusions: This study demonstrates that SIC and RC are epidemiologically distinct tumors with different presentations and outcomes. Minority groups and females are more likely to present with RC. In addition, RC have better prognosis. Further studies are needed to investigate potential biological differences between these two tumors. [Table: see text]