Age-Dependent Opposing Associations of ALBI and PALBI with Prostate Cancer Risk: A Prospective Cohort Study

This study evaluated the associations of serum bilirubin, platelet count, and the composite indices ALBI (Albumin-Bilirubin) and PALBI (Platelet-Albumin-Bilirubin) with prostate cancer risk, with a focus on age-related differences.

We analyzed data from 83,371 men in the Korean Cancer Prevention Study-II (KCPS-II). During a mean follow-up of 14.1 years, 380 incident prostate cancer cases were identified. Associations were examined for total bilirubin, platelet count, ALBI, and PALBI, stratified by age groups (45-55, 55-65, and >65 years). Quartile analyses, trend tests, and sensitivity analyses were conducted. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards models. Age-biomarker interactions and restricted cubic spline (RCS) analyses were performed to assess age-dependent risk patterns.

ALBI and PALBI showed opposing associations with prostate cancer risk across age groups. Among men aged 45-55 years, ALBI was inversely associated with prostate cancer risk (HR: 0.76, 95% CI: 0.63-0.91), whereas PALBI showed a positive association (HR: 1.43, 95% CI: 1.18-1.72). In contrast, among men aged >65 years, ALBI was positively associated with risk (HR: 1.44, 95% CI: 1.13-1.83), while PALBI demonstrated an inverse association (HR: 0.80, 95% CI: 0.64-1.00). RCS analyses confirmed significant age-dependent variations, and biomarker-age interactions were statistically significant (p for interaction < 0.001).

ALBI and PALBI exhibited age-dependent and, in some cases, opposing associations with prostate cancer risk. These findings suggest that age may act as an effect modifier in the relationship between endogenous biomarkers and prostate cancer risk.