Purpose of review: Recent advances in the genomic analysis of breast cancers show promise in better defining endocrine sensitive subtypes. In addition, several key trials have recently reported results that better define the optimal sequence of endocrine agents and approaches to overcome endocrine resistance.
Recent findings: In clinical practice 'luminal' breast cancer is commonly used interchangeably with estrogen receptor positivity by immunohistochemistry. Genomic analysis better defines this subgroup of tumours but also highlights the complexity of the genetic landscape. These advances are discussed, along with pivotal data from contemporary clinical trials of endocrine therapy, the treatment modality most relevant to the 'luminal' subgroup. The review focuses on data from trials in advanced breast cancer. Four studies (FIRST, FACT, SWOG S0226 and SoFEA) have recently reported and improved our understanding of the optimal sequence of endocrine agents, in particular the estrogen receptor downregulator fulvestrant. The TAMRAD and BOLERO2 trials reported significant improvements in outcome with tamoxifen and exemestane, respectively, when these standard agents were combined with the mammalian target of rapamycin inhibitor everolimus.
Summary: Overall these data represent significant advances for women with metastatic breast cancer that will be translated into the early breast cancer setting in the near future.