title: Effect of freeze-thaw cycles on serum measurements of AFP, CEA, CA125 and CA19-9.
abstract: AFP, CEA, CA125 and CA19-9 are commonly used serum tumour markers (TMs) in clinical practice, although their quantification by immunoassay may be influenced by pre-analytical sample handling. Though the effect of repetitive freeze-thaw cycles is generally recognized, it is not clear in detail. The present study measured (CLIA) these TMs in serum samples freshly separated and after each of five freeze-thaw cycles, in which the samples were frozen at -40 degrees C for 10 months at cycle 4 and 2 h at other cycles. Statistical analysis with the General Linear Model for Repeated Measures revealed significant decreases in the measurements of the four TMs, with the least decrease of 6.8 % for CA125 and the most decrease of 18.2 % for CA19-9 after the last cycle, and an overwhelming single cycle decrease of mean 7.7 % at cycle 4 for AFP, CEA and CA125, of 7.5 % and 9.3 % at cycles 4 and 5 for CA19-9. So it seems that measurements of AFP, CEA and CA125 are more readily affected by long-term frozen storage compared with frequent freezing-thawing, while CA19-9 is relatively unstable under both conditions.
authors.affiliation: The Immunoassay Laboratory, Department of Nuclear Medicine, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai, China. gaookok@163.com
authors.forename: Y-C
authors.initials: YC
authors.lastname: Gao
authors.forename: Z-B
authors.initials: ZB
authors.lastname: Yuan
authors.forename: Y-D
authors.initials: YD
authors.lastname: Yang
authors.forename: H-K
authors.initials: HK
authors.lastname: Lu
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood; D018394:CA-125 Antigen / Q000097:blood*; D018395:CA-19-9 Antigen / Q000097:blood*; D002272:Carcinoembryonic Antigen / Q000097:blood*; D005260:Female; D005615:Freezing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood; D015203:Reproducibility of Results; D013048:Specimen Handling / Q000379:methods*; D000509:alpha-Fetoproteins / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D018394:CA-125 Antigen; D018395:CA-19-9 Antigen; D002272:Carcinoembryonic Antigen; D000509:alpha-Fetoproteins