Modest benefits of adjuvant chemotherapy in hormone receptor-positive breast cancer

Abstract

The benefits of adjuvant chemotherapy, endocrine therapy, and trastuzumab therapy are well-established in patients with early breast cancer. Further, there are patient and tumor characteristics that can assist in predicting which patients are more likely to benefit from specific adjuvant therapies. For example, patients whose tumors express estrogen and/or progesterone receptors (ER/PR) derive significant benefit from adjuvant endocrine therapy, whereas those whose tumors do not express these receptors derive very little or no benefit from endocrine therapy [1]. Patients whose tumors overexpress HER2 experience profound benefits from treatment with adjuvant trastuzumab [2,3]. We have recently begun to understand that ER/PR-positive breast cancer also responds differently to chemotherapy than its hormone receptor-negative counterpart. This is not, however, entirely new information. As early as 1978, it was retrospectively observed that ER-positive metastatic breast cancer had lower response rates to a variety of older chemotherapy regimens than did ER-negative disease [4].