- Estrogen receptor (ER) and progesterone receptor (PgR) positivity must be assessed according to American Society of Clinial Oncology (ASCO)/College of American Physicians (CAP) guidelines as either ER or PR ≥ 1% positive nuclear staining. If HER2 IHC is 2+, an evaluation for gene amplification must be performed and the gene must not be amplified. Gene amplification evaluation is not required if evaluation by IHC is 0 or 1+ by institutional standards.