A 3 4 7 -A 7 6 6 A729 oncologists in a two-round Delphi survey both, from the NHS and the society perspective. Unit costs were obtained from national databases. Direct costs included medication and healthcare resources costs (including visits, tests, hospitalizations, surgery, adverse events management and treatment of specific metastases). Indirect costs were estimated using the human-capital approach. Direct and total costs were described for patients with LR and/or MR and for an average patient from a hypothetical cohort of individuals with a BC recurrence. Uncertainties were explored in an univariate sensitivity-analysis. Results: Within a 100-patients'cohort, 7 would have an LR, 90 an MR, and 3 an LR followed by an MR. All patients with an LR would receive targeted therapies combinations. Patients estimated to have an MR received up to 5 treatment lines (5% no treatment; 10%:1L; 13%:2L; 20%:3L; 21%:4L and 31%:5L). Tthe most common treatments in each line were pertuzumabtrastuzumab-taxane (1L), trastuzumab emtansine (2L), lapatinib-capecitabine (3L) and trastuzumab combinations (4-5L). Depending on the type of recurrence and the number of lines received, estimated direct and total costs per patient ranged between € 38,511 (1L) and € 308,869 (5L); total costs between € 50,908 and € 358,000. Direct and total costs for an average patient were € 208,682 and € 235,138 respectively. ConClusions: Direct and indirect costs of treating recurrences need to be integrated in the cost-analysis involving the incorporation or novel targeted agents in the early BC setting to prevent recurrence. Strategies reducing the recurrences risk such as targeted therapies in earlier stages of HER2+ BC would result in significant economic savings for the Spanish NHS and the society.objeCtives: The aim of this study was to describe the estimated costs of recurrent breast cancer (BC) (either locoregional recurrences [LR] or unresectable/metastatic recurrences [MR]) in patients with HER2+ BC in Spain. Methods: The patients'flow, use of healthcare resources and loss of workdays were described by 15 Spanish

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