Recommendations for adjuvant systemic therapies are based on estimates of life expectancy (prognostic markers) and of benefit to therapy (predictive markers). The oestrogen receptor is a classic predictive marker guiding use of anti-oestrogen therapy, and expression profiling appears to select patients more or less likely to benefit. Expression profiling is also under evaluation as a prognostic marker to identify patients who do not need cytotoxic chemotherapy (MINDACT trial). Biological therapy with trastuzu-mab is prescribed on the basis of a predictive test for over-expression of the target growth factor receptor protein, HER2. The ER-PR-HER2-subgroup identifies patients who may benefit selectively from platinum compounds. In radiotherapy, there is also a trend towards delivering fewer, larger fractions of breast radiotherapy to a lower total dose than the historical standard 50 Gy in 25 fractions. Partial breast radiotherapy is under test as a safe and effective alternative to whole-breast radiotherapy for women with low-risk disease, a measure that is also likely to reduce iatrogenic morbidity in long-term survivors. Finally, the identification of subgroups in which radiotherapy can be safely withheld remains a research priority, with age as the single most powerful factor predicting risk of local relapse.