Longitudinal Evaluation of AFP and CEA External Proficiency Testing Reveals Need for Method Harmonization

Area of Science:

• Clinical Chemistry
• Tumor Marker Analysis
• Laboratory Medicine

Background:

• Glycoproteins alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) are established tumor biomarkers.
• International Reference Preparations (IRPs) exist since 1975, but manufacturer-dependent differences suggest a lack of harmonization.
• Previous reports indicated significant variability in AFP and CEA assay results.

Purpose of the Study:

• To analyze longitudinal manufacturer-dependent differences for CEA and AFP tumor markers.
• To assess the harmonization of CEA and AFP assays based on external quality assessment (EQA) data.
• To evaluate assay robustness and compare results against German Medical Association (RiliBÄK) criteria.

Main Methods:

• Analysis of data from 15 international EQA surveys conducted between 2018 and 2022.
• Evaluation of inter- and intra-assay variability for CEA and AFP.
• Comparison of mean 80% and 90% manufacturer collective results with RiliBÄK evaluation criteria.

Main Results:

• Median EQA results for CEA showed manufacturer-dependent differences up to 100% between collectives.
• Median differences for AFP remained mostly below 40%.
• Coefficients of variation were predominantly low for both CEA and AFP assays.

Conclusions:

• Current assays for AFP and CEA detection demonstrate better harmonization than previously suggested.
• The analyzed assays exhibit good robustness.
• Narrowing assessment limits in EQA schemes could further enhance laboratory testing quality for these tumor markers.