Swedish Study Finds Increasing Prevalence of Biliary Tract Cancers Among Younger Adults

A new study out of Sweden suggests biliary tract cancers are increasing in prevalence among younger adults.

The report affirms research from other Western countries suggesting such a trend. The study was published in the European Journal of Cancer.

Corresponding author Cecilia Radkiewicz, MD, PhD, of Sweden’s Karolinska Institute, and colleagues, explained that there are several different subtypes of biliary tract cancers, including gallbladder, intrahepatic, perihilar, and distal. And while many studies pool the cancers into 1 group, the authors said evidence suggests that the prevalence rates for particular subtypes vary from region to region. In addition, they said a number of patient-specific risk factors can increase a patient’s odds of biliary tract cancers. Those include primary sclerosing cholangitis, inflammatory bowel disease, gallstones, liver cirrhosis, and hepatitis B and C.

Previous research has suggested that biliary tract cancers are on the rise, and studies in the United States, Norway, and Japan have examined age disparities in those trends, with the bulk of the evidence suggesting that, at least in those areas, rates of biliary tract cancers are increasing in younger adults. However, Radkiewicz and colleagues said that trend has not been universally observed.

“In a large European, register-based study, trends were inconsistent and an increase was seen in younger adults in the United Kingdom and Ireland, but not Northern Europe (Sweden excluded),” they noted.

The authors therefore wanted to know what the data said about biliary tract cancers and age groups in Sweden in particular.

The investigators consulted the Swedish Cancer Register to find cases of biliary tract cancer in people aged 20-84 who were diagnosed between the years 1993 to 2019. Cases with non-biliary, chiefly hepatocellular histopathology were excluded from the analysis.

The authors compared case rates by subtype, time frame, and annual percentage change for two groups: younger patients (aged 20-54) and older patients (aged 55-84).

Overall, only about 1 in 10 of the 14,083 biliary tract cases were among the younger cohort (1377 cases). When investigators looked at how rates of the cancer subtypes changed through the years, they found rates of gallbladder cancer declined at an annual percentage change of –2.82% (95% CI, –3.18 to –2.46). However, rates of intrahepatic cholangiocarcinoma increased over the same time frame, becoming the most common subtype of biliary tract cancer (annual percentage change 1.74, 95% CI, 1.30-2.18). Perihilar and distal intrahepatic cancers also increased during the study period.

When investigators looked at the increases through the lens of age, they found that intrahepatic and perihilar cholangiocarcinoma both increased in both age groups, but they said the increases in both cases were sharper among the younger cohort than among the older cohort. Among the younger cohort, rates of intrahepatic and perihilar cholangiocarcinoma increased by annual annual percentage changes of 3.01, 95% CI, 1.84-4.20 and 3.93, 95% CI, 2.08-5.81, respectively.

The authors said it is not yet clear exactly why young people seem to be experiencing steeper increases in rates of biliary tract cancer, though they said the strongest risk factor identified was primary sclerosing cholangitis.

Radkiewicz and colleagues concluded that it is important to better understand the reasons behind the trends in order to improve prevention and risk-stratification, and to ensure that targeted interventions make it to patients as early as possible.

Reference

Rahman R, Ludvigsson JF, von Seth E, Lagergren J, Bergquist A, Radkiewicz C. Age trends in biliary tract cancer incidence by anatomical subtype: a Swedish cohort study. Eur J Cancer. 2022;175:291-298. doi:10.1016/j.ejca.2022.08.032