How transferable are recommendations of the era of treating conventionally defined breast cancer for the era of molecularly characterised breast cancer?

Breast cancer is not anymore regarded as a single disease, but consists of diverse subtypes that can be defined by using immunohistochemistry. Risk factors that should determine the onset of chemotherapy include positive lymph node status, high histological grade, high proliferation as measured by Ki-67, low hormone receptor status, positive Her2/neu status, and “triple negative” status (1). But, although adjuvant chemotherapy has an important role in patients with early breast cancer in whom the use of chemotherapy is explicitly indicated, its optimal duration has yet to be defined.