Widening Health Disparities: Increasing Cholangiocarcinoma Incidence in an Underserved Population.

Background and Aims: Cholangiocarcinoma is a relatively rare malignancy with high mortality. In the U.S., incidence rates of cholangiocarcinoma have increased, particularly affecting younger age groups and Hispanic and Asian individuals. We investigated the incidence of cholangiocarcinoma in a largely under-represented, minority population. Methods: We performed a retrospective cohort study from 2005 to 2017 among adults in a county-funded healthcare system in Harris County, Texas. Incidence rate ratios were computed to compare age-standardized rates using U.S. standard population between 2 time periods: 2005-2011 and 2012-2017. Results: We identified 139 cholangiocarcinoma cases (64% intrahepatic, 36% extrahepatic). The median age at diagnosis was 57 years; 62% were Hispanic, and 56% were born outside the U.S. The incidence rate increased from 1.2 to 2.4 per 100,000 person-years (rate ratio 2.1 [95% confidence interval {CI}: 1.5, 3.0]). Hispanic individuals and those aged 40-69 years had the highest rate of incidence increase (respectively, rate ratio: 2.5 [95% CI: 1.6, 4.0] and rate ratio: 2.0 [95% CI: 1.2, 3.0]) between time periods. In 2012-2017, the risk of cholangiocarcinoma among patients with diabetes was 1.4 times relative to those without (relative risk: 1.4; 95% CI: 1.1, 1.5) and 1.2 times among those who were overweight/obese relative to those who were not (relative risk: 1.2; 95% CI: 1.1, 1.6). Conclusion: Incidence of cholangiocarcinoma doubled during the 12-year study period, with Hispanic and middle-aged individuals disproportionately affected. Individuals with diabetes mellitus and those who were overweight or obese had a high risk of being diagnosed with cholangiocarcinoma in the later time period. Further studies should focus on preventing and improving earlier diagnosis of cholangiocarcinoma among Hispanics.