Human epidermal growth factor receptor
2 (HER2) targeted therapy for breast cancer treatment is significantly predicted
by HER2 gene expression. In 2007, the American Society of Clinical Oncology
and the College of American Pathologists (ASCO/CAP)
testing guideline recommendations for
classification of tumors as positive, negative or equivocal. In 2013,
ASCO/CAP revised the guidelines based on concerns that false-negative results in
the denial of beneficial treatment.