ERBB2 and breast cancer: found a higher concordance between HER2 IHC and FISH results using the American Society of Clinical Oncology/College of American Pathologists (ASCO/CAP) 2007 HER2 breast cancer guideline (which uses a 30% cut‐off) compared to the original FDA criteria (using a 10% cut‐off) in a study including 52 serous EC.7