An Autoantibody Based Protein Microarray Blood Test to Enhance the Specificity of a Negative Screening Mammogram

Background: Current screening mammography for breast cancer is associated with misdiagnosis in as many as 30% of cases. Objectives: To develop and clinically evaluate a unique autoantibody based protein microarray blood test to improve the accuracy of breast cancer screening. Materials and Methods: A microarray was constructed from commercial antigens and antigens selected from screened cDNA libraries of breast cancer tissue samples. A training set containing 439 healthy controls and 276 biopsy proven breast cancer cases was used to establish a set of separating models between the two groups. These models were used to assign a diagnosis to 285 blind samples from 120 breast cancer patients and 165 healthy controls. Results: The test identified 82 of the 120 breast cancer patients and 160 of the 165 healthy controls. These results can be translated into a sensitivity of 68.3% [CI: 59% -77%] and a specificity of 97% [CI: 93% -99%], with a PPV for this validation set of 94.3% (CI: 87.10% -98.11%), NPV of 80.81% [CI: 74.62% -86.05%] and an AUC of 89.2% [CI: 78% -87%]. Conclusions: The protein microarray can be utilized to reduce the false negative rate of routine screening mammography. Women with a negative mammography and a negative blood test can be reassured and encouraged to continue routine breast cancer screening. A positive test should alert the physician about the possible presence of a breast cancer not detected by routine screening mammography and drive to perform additional investigation, such as breast ultrasound and MRI.