Factor modification in the association between high-density lipoprotein cholesterol and liver cancer risk in a nationwide cohort

Background/aims The effect modification by smoking and menopausal status in the association between high-density lipoprotein cholesterol (HDL-C) and liver cancer risk has not been reported.Methods This population-based cohort study included 4.486 million cancer-free individuals among those who underwent national cancer screening in 2010 and were followed up until December 2017. We conducted analyses in populations that excluded people with chronic hepatitis B, chronic hepatitis C and liver cirrhosis (Model I) and that included those diseases (Model III). HDL-C level was classified into eight groups at 10-mg/dL intervals. Liver cancer risk by HDL-C was measured using adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).Results During follow-up, 18 795 liver cancers in Model I and 20 610 liver cancers in Model III developed. In Model I, low HDL-C levels (aHR 1.83; 95% CI 1.65-2.04) and extremely high HDL-C levels (aHR 1.24; 95% CI 1.10-1.40) were associated with an increased liver cancer risk compared with a moderate HDL-C level of 50-59mg/dL. This association was similar in both men and women with larger effect size in men (aHR, 1.91; 95% CI, 1.70-2.15). The hazardous association between low HDL-C and liver cancer risk was remarkable in current smokers (aHR, 2.19; 95% CI, 1.84-2.60) and in pre-menopausal women (aHR, 2.91; 95% CI, 1.29-6.58) compared with post-menopausal women (aHR, 1.45; 95% CI, 1.10-1.93). This association was similarly observed in Model III.Conclusions Low and extremely high HDL-C levels were associated with an increased liver cancer risk. The unfavourable association between low HDL-C and liver cancer was remarkable in smokers and pre-menopausal women.