Combined hepatocellular-cholangiocarcinoma: a population level analysis of incidence and mortality trends.

BACKGROUND: The purpose of this study was to explore trends in incidence, incidence-based (IB) mortality, and survival for combined hepatocellular-cholangiocarcinoma (cHCC-CC) utilizing a population-based database to attract people's attention to this disease.

METHODS: The Surveillance, Epidemiology, and End Results (SEER) database was utilized to investigate the incidence and IB mortality for cHCC-CC from 2000 to 2014. Trends in age-adjusted incidence and IB mortality were characterized by the Joinpoint Regression program. The Kaplan-Meier method and log-rank test were utilized to implement survival analyses. Cox regression was utilized to estimate independent predictors of mortality.

RESULTS: The incidence of cHCC-CC was 0.26 per 1,000,000 individuals in 2000 and 0.59 per 1,000,000 individuals in 2014, with an annual percent change (APC) (i.e., the extent of increase in incidence) of 3.84% (95% confidence interval [CI] 1.7-6.1; P < 0.05). The IB mortality also displayed a sustained increase (APC was 4.59%, 95% CI 1.9-7.4; P < 0.05). Compared to patients not undergoing surgery, patients undergoing surgical treatment experienced a significant increase in median survival (3 vs. 28 months; P < 0.001). However, the median survival decreased in patients with tumor size > 5 cm (20 vs. 9 months; P < 0.001). Based on univariate Cox regression analysis, African-American race, distant stage, regionalized stage, tumor size ≥ 5 cm, and no surgery were risk factors for death.

CONCLUSIONS: We identified an overall steady increase in the incidence of cHCC-CC, which indicates that primary prevention strategies for cHCC-CC have not improved much in recent years and that cHCC-CC needs to be taken seriously.