Socioeconomic disparities in incidence, treatment, and survival of intrahepatic cholangiocarcinoma: insights from a nationwide cohort study in Sweden.

Background: The incidence of intrahepatic cholangiocarcinoma (iCCA) is rising globally, yet the role of socioeconomic status (SES) in shaping disease burden and care within universal healthcare systems remains poorly understood. This study assessed SES-related disparities in the incidence, treatment, and survival of iCCA in Sweden. Methods: National registry data were used to identify all adult cases of iCCA diagnosed from 2011 to 2021 (n = 1827). Data from the Swedish quality register for liver cancer were cross-linked with socioeconomic and healthcare registers. Household income- categorised as low (lowest national quartile), medium, or high (highest quartile)-was used as the SES indicator. Incidence rates (IRs), treatment patterns, and survival were analysed across income strata. Findings: The age-standardized IR increased from 1.35 in 2011 to 1.94 per 100,000 person-years in 2021, with the steepest rise observed among men and individuals with low income. Compared to those with high-income, individuals with low income had higher IR ratios of all-stage (1.32, 95% confidence interval [CI]: 1.15-1.52) and late-stage iCCA (1.46, 95% CI: 1.17-1.81). Preventable liver diseases were more prevalent in the low-income patients, while primary sclerosing cholangitis and inflammatory bowel disease were more common among high-income patients. Low income was associated with lower odds of receiving systemic therapy (adjusted odds ratio 0.54, 95% CI: 0.38-0.77) and higher mortality risk among those treated (adjusted hazard ratio 1.34, 95% CI: 1.09-1.65). Interpretation: Despite universal healthcare access, substantial socioeconomic disparities persist in the incidence, treatment, and outcomes of iCCA in Sweden. Funding: The Swedish Cancer Society and The Royal Swedish Academy of Sciences.