[Variation in CEA Values because of Differences in CEA Measurement Methods].

Aim: This study evaluated changes in carcinoembryonic antigen(CEA)values obtained using measurement methods.

Patients and methods: For this analysis, 163 patients with colorectal cancer who underwent new CEA measurements between January and March 2023 were included. Centaur XP or XPT was used as the assay device and ADVIA Centaur CEA was used as the reagent until December 2022(old assay method). The Alinity i system was used as the assay device and CEA-Abbott was used as the reagent after January 2023(new assay method).

Results: Sixteen patients with recurrence and 2 patients with other cancers were excluded. The participants consisted of 76 men and 69 women with a median age of 74 years. The median interval between new and old CEA values was 91 days. The new CEA values were higher than the old CEA values in all but 1 case(99.3%). The mean CEA increased from 2.06 ng/mL to 3.14 ng/mL and was significantly higher when using the new assay method(p<0.0001). An approximate curve was plotted using the old CEA value as x and the new CEA value as y, yielding the following equation: y=1.3281x+0.4112(R2=0.8334).

Conclusion: This study showed that CEA levels differ depending on the measurement method used.