Progress and promise: highlights of the international expert consensus on the primary therapy of early breast cancer 2007

Abstract

The 10th St Gallen (Switzerland) expert consensus meeting in March 2007 refined and extended a target-oriented approach to adjuvant systemic therapy of early breast cancer. Target definition is inextricably intertwined with the availability of target-specific therapeutic agents. Since 2005, the presence of HER2 on the cell surface has been used as an effective target for trastuzumab much as steroid hormone receptors are targets for endocrine therapies. An expert Panel reaffirmed the primary importance of determining endocrine responsiveness of the cancer as a first approach to selecting systemic therapy. Three categories were acknowledged: highly endocrine responsive, incompletely endocrine responsive and endocrine non-responsive. The Panel accepted HER2-positivity to assign trastuzumab, and noted that adjuvant trastuzumab has only been assessed together with chemotherapy. They largely endorsed previous definitions of risk categories. While recognizing the existence of several molecularly-based tools for risk stratification, the Panel preferred to recommend the use of high-quality standard histopathological assessment for both risk allocation and target identification. Chemotherapy, although largely lacking specific target information, is the only option in cases which are both endocrine receptor-negative and HER2-negative. Chemotherapy is conventionally given with or preceding trastuzumab for patients with HER2-positive disease, and may be used for patients with endocrine responsive disease in cases where the sufficiency of endocrine therapy alone is uncertain. Recommendations are provided not as specific therapy guidelines but rather as a general guidance emphasizing main principles for tailoring therapeutic choice.