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. The evolution of metastatic breast cancer has changed considerably in the last years with the approval of new drugs. In fact, already in 2003 Giordano et al showed that the prognosis of metastatic breast cancer patients was improved significantly from 1970's to 2000 with a median survival of 15 months in the early 1970's compared with 60 months in the last 1990's. This significant survival gain was obtained with introduction of new drugs as hormonal, chemotherapeutic and biological agents. The greater availability of drugs has led to an increase in number of lines of treatment receiving by metastatic breast cancer patients. However, there are few published data on actual duration of metastatic breast cancer treatments. Moreover, there is no evidence to support a real impact on survival of treatments beyond the second-third line. Recently, a retrospective analysis of about 199 metastatic breast cancer patients treated with chemotherapy showed that tumor subtype is associated with the duration and number of lines of chemotherapy (for example HER positive versus triple-negative patients) .