Much has been learned from clinical trials conducted in what we might call the pre-subtype era. We know that systemic therapies given in the adjuvant setting improve survival, that anthracyclines and taxanes are the best cytotoxics to use, that endocrine therapy is effective, especially when given for many years, and that aromatase inhibitors are slightly better at preventing relapses than tamoxifen.
However we have now entered an era where clinical trials have to be designed with the likely breast cancer subtype in mind. This makes trials more exciting and interesting to do, but also more complicated and expensive. Several of these trials will be reviewed, encompassing ER positive disease, HER2 positive disease and immunotherapy, and the adjuvant use of PARP inhibitors in women with BRCA mutations.