Umair M. Nasir, DO, Sushil Ahlawat, MD, Qi Yu, MD; Rutgers New Jersey Medical School, Newark, NJ
Introduction: Up to 90% of all cholangiocarcinomas (CCA) are classified as extrahepatic. Previous studies have shown a plateau of the trend in age-adjusted incidence for extrahepatic CCA in contrast to an increasing trend in intrahepatic CCA. However, more recent data have not been explored, especially in the context of race and ethnicity. Furthermore, even though differences in incidence of CCA have been noted between racial and ethnic groups, differences in survival among these groups have not been examined for extrahepatic CCA. Methods: Patients with extrahepatic CCA recorded in the SEER database from 1975-2016 were characterized according to race (White, Black, American Indian/Alaska Native or AI, and Asian/Pacific Islander or API) and ethnicity (Hispanic, non-Hispanic). APC were calculated by fitting a least-squares regression line to the natural logarithm of the rates using the calendar year as a regressor variable. Relative survival rates were calculated using the Ederer II method. Results: Data from 9 cancer registries from 1975-2016 in the US show that the overall age-adjusted incidence rate (out of 100,000) of extrahepatic CCA have remained stable at 1.9 with an annual percentage change (APC) of 0.304 (p=0.086). While no significant APC was noted in Whites, significant APC were noted in Blacks (1.071, p=0.015) and patients of other races (0.765, p=0.028 for AI and API grouped together). More recent data including an additional 4 registries revealed a significant increase of extrahepatic CCA between 1992-2016 overall (APC 1.6, p< 0.001). The APC of incidence rates was significant in Whites (1.536, p< 0.001) and non-Hispanic Whites (1.304, p< 0.001), Blacks (1.875, p-value 0.010) and non-Hispanic blacks (1.953, p=0.007), and Hispanics of all races (1.800, p< 0.001). APC were not significant in AI or API, although APC was negative for AI (-2.080, p=0.174). Compared with the survival rate of non-Hispanic Whites (42.8%), every racial and ethnic group except for API had a significantly lower rate at 12 months for extrahepatic CCA. This difference was no longer seen at 24 months and beyond. Discussion: Although it is unclear whether or not the incidence of extrahepatic CCA has changed overall, this study suggests that the decrease in incidence of extrahepatic CCA in non-Black, non-White populations may be offset by an increase in other populations. Furthermore, non-Hispanic Whites and API appear to have an early survival advantage, though it is not sustained.
Disclosures: Umair Nasir indicated no relevant financial relationships. Sushil Ahlawat indicated no relevant financial relationships. Qi Yu indicated no relevant financial relationships.