 Breast cancer is the most common cancer in many countries: in Italy about 48.000 new breast cancers are diagnosed every year and, despite improvements in diagnosis and therapy, about 13.000 women die every year for this disease . About 6-7 of breast cancer patients are metastatic at diagnosis , while the majority of patients with stage IV has a previous history of breast cancer that has already been treated. According to various prognostic factors tumor size, lymph nodes involvement, grading, hormone receptors status, HER-2 status, in the worst-case scenario, more than 30 of node-negative breast cancer patients and more than 70 of node-positive patients relapse2. 