An estimated 297 790 women will receive a diagnosis of breast cancer in the US in 2023, and nearly 43 170 women will die of the disease.
1 Assessment of possible expression of estrogen receptor (ER), progesterone receptor (PR), and erb-B2 receptor tyrosine kinase 2 (
ERBB2 [formerly
HER2]) is standard in identifying the most suitable breast cancer treatment and determining prognosis. Breast cancer is grouped into 3 subtypes: hormone receptor positive and
ERBB2 negative (approximately 65%),
ERBB2 amplified (approximately 5%-20%), and triple negative (approximately 5%).
2 The characterization of subtypes has changed how patients with breast cancer are treated.
3 Because of this, testing for ER, PR, and
ERBB2 expression is the recommended standard of care for all of those with a diagnosis of invasive breast cancer.
4