The tests are usually conducted on a sample of cancer tissue obtained through a biopsy. The two most common methods used are Immunohistochemistry (IHC) and Fluorescence In Situ Hybridization (FISH). IHC detects the presence of estrogen receptors (ER) and progesterone receptors (PR) using specific antibodies that bind to these receptors. FISH is generally used to detect HER2/neu receptors, which can also play a role in breast cancer.
