Clinics and Research in Hepatology and Gastroenterology
Original articleEpidemiology of Cholangiocarcinoma; United States Incidence and Mortality Trends
Introduction
Cholangiocarcinoma (CCA) is a relatively rare, aggressive, and diverse group of malignancies arising from the epithelial cells of the biliary duct [1]. CCA can originate from anywhere along the bile duct and has been sub-classified anatomically into intrahepatic cholangiocarcinoma (iCCA) arising from bile ducts from within liver, and extrahepatic cholangiocarcinoma (eCCA) where the CCA arises from the bile duct outside the liver [2], [3]. CCA comprises 3% of all gastrointestinal tumors and is the second most common liver cancer [4], [5]. CCA is clinically silent and has a poor prognosis, with a late or delayed presentation in most cases. Many studies have raised the concern that the incidence and mortality related to specific subtypes of CCA have been increasing [4], [6], [7]. Several risk factors, such as obesity, diabetes, smoking, alcohol, parasitic infections, HBV, and HCV infections, have been linked to CCA [8], [9], [10], [11], [12]. Given the low rates of early detection, clinical silence, and poor prognosis, further CCA research remains an unmet need around the world [13], [14]. Therefore, there is a need for a comprehensive understanding of recent trends in incidence and mortality, which can help physicians and researchers focus on the specific factors contributing to morbidity and mortality of CCA. To our knowledge, large cohort-based epidemiologic studies investigating temporal trends of CCA have not been performed [15]; hence, the current study may help understand the trend of the disease over time.
Section snippets
Data source
We used SEER*stat software (version 8.3.5) to obtain data of cholangiocarcinoma cases diagnosed during 2000-2015 from SEER 18 registries [16], “Incidence - SEER 18 Regs Research Data, Nov 2017 Sub (2000-2015)”, a database that covers approximately 30% of the United States population (based on 2010 census) [17].
Study population
The study includes patients with cholangiocarcinoma diagnosed between 2000 and 2015 in United States; codes used for this selection are mentioned in supplementary Table 1. We excluded
Baseline characteristics
We identified 16,189 cholangiocarcinoma cases that were diagnosed between 2000 and 2015 in the United States, with about two-thirds of the cases (64.4%) being intrahepatic (Table 1). Nearly half of the cases were males (51.3%). Most patients were whites (78.4%) and older than 65 years (63%).
During the study period, 13,121 cholangiocarcinoma patients died and were included in the incidence-based mortality analysis (Table 2).
Discussion
Our study revealed an overall increase in incidence and incidence-based mortality rates of CCA during 2000-2015. CCA remains a challenge for clinicians to detect cancer in early stages and decrease the progression of the disease. Recently, few studies evaluated the incidence of CCA; their results are consistent with our findings of an overall increase in incidence rates during the study period except for specific subgroups [12], [15], [21]. Moreover, the last decade has witnessed a dramatic
Conclusions
In summary, our findings reveal that there were increasing trends in the incidence and mortality rates of cholangiocarcinoma. Further studies are needed to determine the potential risk factors and mechanisms related to the increased trends in CCA in the USA. Understanding and defining the determinants of the ethnic and gender differences are informing to clinical practitioners, as they may result in generating diverse strategies for the prevention, early detection, and management of CCA.
Disclosure of interest
The authors declare that they have no competing interest.
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