Comparison of the PharmDx immunohistochemical system with standard methods for assessing estrogen and progesterone receptors in invasive carcinoma of the breast.

AIM: Accurate assessment of estrogen receptor (ER) and progesterone receptor (PR) status of breast cancers is essential for selecting patients for endocrine treatment. This study aimed to compare immunohistochemistry for these markers using the pharmDx system and standard methods. METHODS: Sections of 203 core biopsies of invasive carcinoma of the breast were stained for ER and PR using the pharmDx system and standard methods. RESULTS: Using a cutoff of H score of 10, there was agreement between the 2 methods in 201 tumors (99%) for both ER and PR. Using a cutoff of 1% staining there was agreement of 99.5% for ER and 96% for PR. CONCLUSIONS: The pharmDx system shows good agreement with standard methods for assessing ER and PR in breast cancer.