Biliary tract cancer incidence and trends in the United States by demographic group, 1999-2013

Abstract

Background: Biliary tract cancers (BTCs) are rare but deadly cancers (gallbladder cancer [GBC], intrahepatic cholangiocarcinoma [ICC], extrahepatic cholangiocarcinoma [ECC], and ampulla of Vater cancer [AVC]). A recent US study reported increasing GBC incidence among people younger than 45 years and blacks; however, it did not examine trends for other biliary tract sites.

Methods: This study characterized demographic differences in BTC incidence rates and time trends by anatomic site. Population-based North American Association of Central Cancer Registries data were used to calculate age-adjusted incidence rates, incidence rate ratios (IRRs), and estimated annual percent changes (eAPCs) for 1999-2013 by site and demographic group. For sites with significant differences in eAPC by age group, IRRs were compared by age group.

Results: GBC incidence rates declined among women (eAPC, -0.5%/y; P = .01) and all racial/ethnic groups except for non-Hispanic blacks, among whom rates increased (1.8%/y; P < .0001). Although GBC rates increased among 18- to 44-year-olds (eAPC, 1.8%/y; P = .01), they decreased among people 45 years old or older (-0.4%/y; P = .009). Sex (P < .0001) and racial/ethnic differences (P = .003 to .02) in GBC incidence were larger for younger people than older people. During this period, ICC (eAPC, 3.2%/y; P < .0001) and ECC rates (1.8%/y; P = .001) steadily increased across sex and racial/ethnic groups. Although AVC incidence rates increased among younger adults (eAPC, 1.8%/y; P = .03) but not older adults (-0.20%/y; P = .30), sex and racial/ethnic IRRs did not differ by age.

Conclusions: Differential patterns of BTC rates and temporal trends have been identified by anatomic site and demographic groups. These findings highlight the need for large pooling projects to evaluate BTC risk factors by anatomic site.

Keywords: United States; biliary tract; cancer; incidence; trends.

Figure 1:

Abbreviations: NH (non-Hispanic) Age-adjusted rates of biliary tract cancers per 1,000,000 person-years in the United States in three-year periods between 1999 and 2013 plotted at the mid-point for each period by cancer site and sex (1A to 1D), race/ethnicity (1E to 1H), and age group (1I to 1L). The fitted linear trends were plotted through age-adjusted rates of biliary tract cancers per 1,000,000 person-years in the United States in three-year periods between 1999 and 2013 modeled in Joinpoint specifying zero joinpoints. Source: Thirty-eight National Program of Cancer Registries and Surveillance, Epidemiology, and End Results registries that met data quality standards of the North American Association of Central Cancer Registries (NAACCR) for the period 1999–2013

Figure 2:

Abbreviations: AVC, ampulla of Vater cancer; CI, confidence interval; GBC, gallbladder cancer; IRR, incidence rate ratio; NHB, non-Hispanic black race/ethnicity; NHO, non-Hispanic other race/ethnicity; NHW, non-Hispanic white race/ethnicity. Incidence rate ratios (IRRs) and 95% CIs for female-to-male, black-to-white, Hispanic-to-white, and other-to-white comparisons of age-adjusted incidence rates stratified by age group (black solid boxes for 18 to 44-year-olds, and open boxes for ≥45-year-olds) by cancer site [2A-gallbadder cancer (GBC) and 2B-ampulla of Vater (AVC)] in the United States, 1999–2013, P-values correspond to the Wald test for the difference between incidence rate ratios for younger vs. older people. Source: Thirty-eight National Program of Cancer Registries and Surveillance, Epidemiology, and End Results registries that met data quality standards of the North American Association of Central Cancer Registries (NAACCR) for the period 1999–2013.