Modeling the time-related fluctuations of AFP and PIVKA-II serum levels in patients with cirrhosis undergoing surveillance for hepatocellular carcinoma

BACKGROUND: The time-related variability of HCC biomarkers has not been investigated so far. OBJECTIVE: To assess the changes of alpha-fetoprotein (AFP) and protein induced by vitamin-K absence/antagonist-II (PIVKA-II) in patients with HCC (HCC+) as compared to patients without HCC (HCC-). METHODS: AFP and PIVKA-II were measured by a single laboratory using an automated chemiluminescent-enzyme-immunoassay (Fujirebio Inc., Tokyo, Japan) in 1163 sera of 418 cirrhotics (31.1% HBV, 58.6% HCV, 10.3% non-viral etiology) undergoing ultrasound HCC surveillance. The mean (range) number of effective time-points available for analysis was 2.8 (2.0 to 3.0); 124 patients with HCC were matched with 294 who remained HCC free for at least 12 months after the last specimen. AFP and PIVKA-II changes were estimated over time by means of a random-effect generalized least squares (RE-GLS) regression model under the missingness at random assumption. RESULTS: Patients with and without HCC had comparable chronic liver disease etiology and staging. AFP/PIVKA-II median (25th; 75th percentile) values at the latest time-point were 4.2 (2.6; 8.6) ng/mL/32 (25; 42) mAU/mL in HCC-and 8.4 (4.4; 32.1) ng/mL/66 (32; 192) mAU/mL in HCC+ (p< 0.001). Log10AFP and log10PIVKA-II time-changes differed in HCC+ and HCC-patients. In HCC+ patients, both log10AFP and log10PIVKA-II showed an increasing trend over time. In HCC-patients, log10PIVKA-II variations were minimal as compared to log10AFP variations. The percent increase of log10AFP at 6 months vs. baseline was 11% (95%CI 5 to 17%) and 5% (95%CI 1 to 8%) for log10PIVKA-II in HCC+vs. HCC-patients. CONCLUSIONS: The present retrospective study of the biological variability of AFP and PIVKA-II suggests that their time-related changes may serve as potential predictors of HCC. This topic needs to be addressed by longitudinal studies.