Technical validation of an autoantibody test for lung cancer

BACKGROUND Publications on autoantibodies to tumour-associated antigens (TAAs) have failed to show either calibration or reproducibility data. The validation of a panel of six TAAs to which autoantibodies have been described is reported here. MATERIALS AND METHODS Three separate groups of patients with newly diagnosed lung cancer were identified, along with control individuals, and their samples used to validate an enzyme-linked immunosorbant assay. Precision, linearity, assay reproducibility and antigen batch reproducibility were all assessed. RESULTS For between-replicate error, samples with higher signals gave coefficients of variation (CVs) in the range 7%-15%. CVs for between-plate variation were only 1%-2% higher. For between-run error, CVs were in the range 15%-28%. In linearity studies, the slope was close to 1.0 and correlation coefficient values were generally >0.8. The sensitivity and specificity of individual batches of antigen varied slightly between groups of patients; however, the sensitivity and specificity of the panel of antigens as a whole remained constant. The validity of the calibration system was demonstrated. CONCLUSIONS A calibrated six-panel assay of TAAs has been validated for identifying nearly 40% of primary lung cancers via a peripheral blood test. Levels of reproducibility, precision and linearity would be acceptable for an assay used in a regulated clinical setting.