Pathologists' Guideline Recommendations for Immunohistochemical Testing of Estrogen and Progesterone Receptors in Breast Cancer.

Expression of the hormone receptors (estrogen receptor (ER) and progesterone receptor (PR)) as well as overexpression / amplification of the human epi-dermal growth factor receptor-2 (HER2) have not only been identified as important prognostic factors among patients with breast cancer. They have also been characterized as essential predictive factors for benefit derivable from endocrine treatment or immunologic therapies directed against HER2, respectively. Hence, reliable determination of hormone receptor and HER2 status among patients with breast cancer has become of utmost importance. The need for developing and promoting standard methodologies for the assessment of the individual disease phenotype has previously been acknowledged by publication of novel guidelines for HER2 testing. For HER2 testing, these guidelines have been developed in 2007 by the American Society of Clinical Oncology (ASCO) in conjunction with the American College of Pathology (CAP). Recently, ASCO/CAP have acknowledged the need for standardized assessment of hormone receptor status.We asked two experts in the field of breast pathology whether the new guidelines on hormone receptor testing would change current practice of hormone receptor status measurement in Germany and how they should be viewed in face of novel developments regarding gene expression based multigene predictive factors.Cornelia Liedtke, Münster and Oleg Gluz, Wuppertal.