Biological variations of seven tumor markers

We sought to identify biological variations in the following tumor markers: pepsinogen I (PGI), pepsinogen II (PGII), carbohydrate antigen 724 (CA724), neuron-specific enolase (NSE), pro-gastrin-releasing peptide (ProGRP), carcinoembryonic antigen (CEA), and carbohydrate antigen 199 (CA199). Serum samples were collected from 20 healthy Chinese individuals over 5 days. Samples were then screened for the presence of the seven aforementioned tumor markers. Within-individual coefficient of variation (CVI), between-individual coefficient of variation (CVG), confidence interval (CI) of biological variations, index of individuality (II), and the reference change value (RCV) of the seven tumor markers were calculated. Of the 7 tumor markers, index of individuality was all < 1.0. ProGRP showed the lowest CVI and CVG, at 4.75% (CI: 3.96%–5.94%) and 16.42% (CI: 12.32%‐24.61%), respectively. The 95% and 99% RCVs for ProGRP were 14.68 and 19.32, respectively, and were the lowest of the markers. In contrast, the CVI and CVG for CA724 were the highest, at 16.06% (CI: 13.83%–19.17%) and 96.95% (CI: 73.73%–141.59%), respectively. The 95% and 99% RCVs for CA724 were the highest, at 45.89 and 60.41, respectively. Our findings provide additional information regarding the biological variation of tumor markers, and could be applied in a clinical setting.