New approaches for the classification of early breast cancer, a heterogeneous disease entity
The proportion of breast cancers detected in the very early stages (in situ and invasive breast cancers <15 mm) in daily practice has significantly increased, thanks to breast screening, breast awareness and improved detection methods. Most of these tumours show less aggressive biological phenotype than their more advanced counterparts, and have an excellent long-term prognosis without applying oncological treatments. The identification of the minority of cancers with a poor prognosis and their appropriate therapy is the real challenge. In fact, neither the first-generation prognostic factors (the tumour size, the lymph node status and the histology grade), nor the usual additional parameters (the receptor status and proliferation markers) are reliable enough for the estimation of the outcome. Likewise, the conventional predictive factors such as the ER, PR and HER2 status are not sufficient for the individualization of therapy in those cases that need oncological therapy. This overview points to the pressing need and the emerging elements of a potential new classification system of early breast cancer including the consideration of the mammographic appearance, the extent of the disease instead of just the largest dimension of the main invasive focus and the mode of detection or the use of molecular tests.