However, an earlier study of 500 primary and metastatic breast cancer tested the concordance of the two tests and showed the proportion of HER2 1+/2+ scores to be 28% and 11.6% by the 4B5 and HercepTest respectively, with several tumours designated as HER2 0 by the HercepTest, classified as 1+/2+ (i.e., HER2-low) by the 4B5 assay. This evidence concerns the gene ERBB2 and neoplasm.