Metastatic breast cancer: we do need primary cost data.

The lifetime cost of metastatic breast cancer is a key component for the economic evaluations of targeted therapies and biomarkers. In the literature, only few cost studies are available and provide discordant cost estimates for the management of metastatic recurrences. Our objective was to assess the lifetime costs of metastatic breast cancer and to investigate cost variability using primary cost data. We used individual data from a cohort of 290 French women treated at the Gustave Roussy Institute and who had died between 2005 and 2008. We separately analysed the determinants for survival after metastatic recurrence and for the monthly cost using two different models. The mean survival time after recurrence was 24.8 months. The mean hospital cost per patient amounted to € 36,516 and the mean cost per month € 3764. We identified three prognostic factors: age at breast cancer diagnosis, the histological grade and the site of the first recurrence. The factors significantly associated with the cost per month were hospitalisation in a palliative care unit, trastuzumab treatment, the number of sites of recurrence and whether or not the patient had died during the last hospital stay. We identified cost drivers of the lifetime costs of metastatic breast cancer. This provides useful information for the design of future economic studies. We also provide cost estimates in homogeneous subgroups of patients defined by patient characteristics and by the type of care received.