An Examination of Liver Cancer Incidence in California.

Background and objective: Liver cancer is composed of 2 main types, hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). After years of increasing HCC incidence rates in the United States, declines have been noted in recent years, but CCA incidence rates have continued increasing. Given these variable trends; documented disparities by sex, age, and race/ethnicity; and shifting risk factors from viral infection (hepatitis B and C) to metabolic causes (obesity, diabetes, nonalcoholic fatty liver disease), we sought to assess the incidence rate trends for HCC and CCA in California to inform whether California trends are similar to those observed in the United States as a whole, whether these trends have continued in the most recent years for which data is available, and to identify at-risk groups that may benefit from targeted intervention.

Methods: Using SEER*Stat software, we calculated age-adjusted incidence rates (AAIR) by sex, age group, and race/ethnicity for patients aged ≥40 years diagnosed with HCC and CCA from 2010 to 2021 identified in the California Cancer Registry. We assessed the annual percent change (APC) over this period for each subgroup using Joinpoint software.

Results: For HCC, the AAIR significantly decreased for men (-2.68%) and women (-2.23%) since 2014. Significant decreases were observed for men among all racial/ethnic groups, but among women, decreases were only seen in Black and Asian/Pacific Islander patients. Decreases in AAIR were greatest among those aged 40 to 64 years (men, -7.01%; women, -7.79%) and increases were observed for men aged ≥75 years since 2010 (1.15%). For CCA, the AAIR significantly increased for men aged ≥75 years (2.8%) and for women in all age groups. Only White men had decreasing AAIRs.

Conclusion: HCC AAIR trends have declined in California, but not for all groups. Older men and Hispanic and White women did not experience the same reductions in HCC AAIR observed in other groups. CCA AAIR trends have increased among nearly all groups for women. Future research should focus on evaluating risk factors by liver cancer sub-type, and regular screening of individuals with risk factors should be considered.