- Tumor considered potentially hormone-sensitive, i.e. presence by IHC of hormone receptors for estrogens (ER+ for more than 10% of cells) and/or progesterone (Pg+ for more than 10% of cells) or both. This expression may have been detected on the primary tumor or at a metastatic site. The method used will be reassessed by IHC if it involves a radioligand technique whenever it is possible to obtain histological material.