In western countries, every woman out of eight will develop breast cancer. Over the last two decades, the incidence has considerably increased, but mortality has remained stable and begins to decrease in Europe and the United-States, probably because of new therapy, changes in the use of hormone replacement therapy in postmenopausal women and early diagnosis. Breast cancer is still the first cause of death by cancer in woman under 65. "Triple negative" a breast cancer, a subtype representing 10% of all breast cancers, is characterised by the absence of receptors to oestrogen, progesterone and no histochemical expression of HER-2 growth factor. This subtype carries a poor prognosis and a high incidence of early metastatic recurrence. Furthermore, no target therapy can be defined up to now in this subtype. Thus, identification of new target therapy and prediction of tumoral response to various treatments could help in the global understanding of patients affected by this particularly aggressive type of breast cancer.