ERBB2 and breast cancer: In fact, we and others have shown that SNPs which occur in the epidermal growth factor receptor (EGFR), ERBB2, ERBB3 or ERBB4 genes (HER-family genes) can be associated with either a worse relapse free survival (RFS) or worse overall survival (OS) rates in women with HER2-positive breast cancer who received adjuvant trastuzumab as part of their treatment regimen [9,10].