Impact of clinical and non-clinical factors on the choice of HER2 test for breast cancer

Evaluation of HER2 status is critical in determining appropriate treatment for breast cancer. Currently, Fluorescence In Situ Hybridization (FISH) and Immunohistochemistry (IHC) are the FDA-approved tests. Studies show, FISH is superior to IHC in accuracy and prediction of clinical outcomes with respect to response to anti-human epidermal growth factor receptor 2 (HER2) therapy trastuzumab. The impact of factors on choice of test for HER2 detection was determined using logistic regression. We show that geographic location, cancer stage, and diagnosis date have significant effects on choice of test. These findings indicate that disparities may be present in breast cancer care, and highlight the importance of testing guidelines.