Causal association between serum bilirubin and ischemic stroke: multivariable Mendelian randomization

Sex-Specific Associations of Total Bilirubin, ALBI, and PALBI with Lung Cancer Risk: Interactions with Smoking and Alcohol

Background: Bilirubin is a potent endogenous antioxidant that plays a key role in regulating oxidative stress and inflammation, both closely linked to lung carcinogenesis. This study reinterprets the ALBI (Albumin-Bilirubin) and PALBI (Platelet-Albumin-Bilirubin) indices as composite markers of antioxidant and inflammatory status and evaluates their associations with lung cancer risk by sex, including stratified analyses by major lifestyle factors such as smoking and alcohol use. Methods: This study utilized data from the Korean Cancer Prevention Study-II (KCPS-II) cohort, which included 133,630 participants. During a mean follow-up of 13.5 years, 721 incident lung cancer cases were identified. Serum bilirubin and the ALBI and PALBI indices were analyzed by sex, and quartile-based and trend analyses were conducted. Stratified analyses by smoking and alcohol status (never, former, current, ever) and intensity were performed to assess potential effect modification. Cox proportional hazards regression models were used to estimate HRs and 95% CIs. Results: A 1SD increase in total bilirubin and ALBI was inversely associated with lung cancer risk in men (HR: 0.83, 95% CI: 0.75-0.91; HR: 0.86, 95% CI: 0.79-0.94, respectively), whereas PALBI showed a positive association (HR: 1.17, 95% CI: 1.07-1.28). In contrast, in women, total bilirubin and ALBI showed positive associations (HR: 1.19, 95% CI: 1.00-1.40; HR: 1.19, 95% CI: 1.02-1.40, respectively), while PALBI was inversely associated (HR: 0.82, 95% CI: 0.69-0.97). These associations were significant among men who were smokers (former, current, ever) and men who drank alcohol (current, ever), whereas in women, significance was observed only among never drinkers. Stronger interactions were observed in men who were heavy smokers and low-to-moderate drinkers. Conclusions: Bilirubin and the ALBI and PALBI indices exhibit sex-specific and contrasting associations with lung cancer risk, highlighting the need to consider sex-based physiological differences in cancer risk assessment.

Association Between Creatinine and Lung Cancer Risk in Men Smokers: A Comparative Analysis with Antioxidant Biomarkers from the KCPS-II Cohort

Bilirubin, albumin, and uric acid are established endogenous antioxidant biomarkers, whereas the antioxidant role of creatinine has not yet been fully clarified. As a byproduct of creatine metabolism, creatinine may reflect underlying metabolic activity and redox balance, particularly under conditions of oxidative stress such as cigarette smoking. This study aimed to evaluate the associations between serum creatinine and other antioxidant biomarkers and lung cancer risk, stratified by smoking status. We analyzed 83,371 cancer-free men from the Korean Cancer Prevention Study II (KCPS II) cohort. During a mean follow-up of 13.5 years, 533 incident lung cancer cases were identified. Serum creatinine, total bilirubin, albumin, and uric acid were measured. Smoking status classified participants as never-, former, and ever-smokers, with ever-smokers including both current and former smokers. Cox proportional hazards regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs), stratified by smoking status. Biomarkers were also analyzed by quartiles and linear trends. A single standard deviation increase in serum creatinine was significantly and inversely associated with lung cancer risk among former smokers (HR: 0.774, 95% CI: 0.620 to 0.967) and ever-smokers (HR: 0.823, 95% CI: 0.716 to 0.945). Total bilirubin also showed significant inverse associations in former smokers (HR: 0.826, 95% CI: 0.705 to 0.967) and ever-smokers (HR: 0.785, 95% CI: 0.708 to 0.870). Albumin was inversely associated only with ever-smokers (HR: 0.878, 95% CI: 0.807 to 0.955), while uric acid showed inverse associations with both former smokers (HR: 0.832, 95% CI: 0.699 to 0.989) and ever-smokers (HR: 0.847, 95% CI: 0.760 to 0.944). None of the biomarkers showed significant associations among never-smokers. Serum creatinine and other endogenous antioxidant biomarkers were inversely associated with lung cancer risk, particularly in individuals with a history of smoking exposure.