Neo-adjuvant systemic treatment (NST) is nowadays the standard of care in locally advanced breast cancer [1]. Although many studies have shown that the administration of chemotherapy before or after surgery does not influence the prognosis, NST presents advantages such as in vivo assessment of tumor response to specific chemotherapeutic agents, treatment of micrometastatic disease and most importantly the chance for more patient to undergo conserving-surgery [2,3] The importance of assessing tumor residual exent is related to the evidence that a complete response after NST is a positive prognostic factor in predicting long-term survival [4].
In the last years magnetic resonance imaging has acquired a primary role in many aspect of breast disease [5,6]in particular becoming the method of choice for the evaluation of response to neo-adjuvant systemic treatment [7,8]. Despite its superiority over conventional imaging modalities in this setting, MRI has been associated of over- or understimation of residual extent of disease, possibly related to pattern of tumor response, chemotherapeutic agent or reactive changes induced by NST [7,9] Some authors raised the hypothesis that also the molecular characteristics of the tumor may influence the accuracy of MRI in the evaluation of the response [10,11]. Hormone receptor expression, oestrogen (ER) and progesterone (PR), and the over-expression/amplification of the Her2neu/ERB2 (HER) oncogene allow to subdivide breast cancer into three main molecular subtypes:
- luminal (LUM): ER+ or PR+ and HER2+/- tumors
- HER2+: ER-,PR- and HER2+ tumors
- triple negative (TN):ER-,PR- and HER2- tumors).
These subgroups reflect the pattern of gene expression of the two main type of cells of the breast: epithelial (luminal) and myoepithelial (basal) cells [12] (FIG.1).
The aim of the study is to evaluate the overall and by molecular subtype accuraces of breast MRI in demonstrating residual tumor after NST.
