Use of chemotherapy for patients with estrogen receptor (ER)-positive breast 
cancer has been a conflicting issue. Recent studies have identified predictive 
markers allowing identification of poor-prognosis ER-positive breast cancers in 
need of more aggressive therapy. In general, tumours belonging to the so-called 
luminal B class, tumours expressing a high Ki67, human epidermal growth factor 
receptor 2 (HER-2) overexpression or a high score on the Oncotype DX gene 
expression profile reveal a poor prognosis compared with ER-rich tumours of the 
luminal A class. In contrast, recent studies have shown these tumours, 
contrasting tumours of the luminal A class, to benefit from more aggressive 
anthracycline-containing chemotherapy including a taxane. In the case of 
metastatic disease, patients with HER-2-positive, ER-positive tumours may 
benefit from having endocrine therapy and an anti-HER-2 agent administered in 
combination.