Abstract: Objective To evaluate the consistency of squamous cell carcinoma antigen (SCCA) results between Roche cobase 602 and Abbott Architect i2000 SR automated immunoassay system. 
Methods A total of 4 231 clinical serum samples were collected during the parallel detection of methodological changes in the Department of Clinical Laboratory, and the SCCA levels were detected by the above immunoassay systems. The precision was evaluated by referring to CLSIEP15-A2 protocols. The data of 138cases of SCCA results were selected by random sampling, and the correlation, consistency and deviation of SCCA results of the two systems were analyzed by correlation analysis, regression analysis and consistency test. The SCCA results of 4 231 patients were analyzed by Kappa analysis, and the results of Roche system were corrected by linear regression equation. The diagnostic coincidence rate, positive coincidence rate and negative coincidence rate of the two systems before and after correction were calculated, to evaluate the diagnostic consistency of the two systems. 
Results The precision of the two detection systems was 2.35%-3.56% and 0.99%-1.70% respectively, and there was a strong correlation between them (rs=0.939). The Passing Bablok regression equation was as follows: y=0.156±1.034x (intercept=0.156, slope=1.034), the average percentage bias was within the acceptable range (-9.30%), but more than 5% of data points fell outside the 95% control limit. The folding of the mountain map was close to 0 (-0.28 mg/L). The intra-group correlation coefficient was 0.912 (95%CI: 0.880-0.937). After correction, the total coincidence rate, positive coincidence rate and Kappa value of Roche and Abbott SCCA results increased from 92.86%, 54.91%, and 0.660 to 93.83%, 90.98% and 0.778, respectively. 
Conclusion The two SCCA detection systems have good correlation and consistency, but there is a systematic deviation. Therefore, the results can be transformed by regression equation before clinical judgment. 

Key words: carcinoma, squamous cell, Roche automatic immunoassay, Abbott automated immunoassay