Performance of time to discontinuation and time to next treatment as proxy measures compared to direct observation of progression-free survival
Real-world data sources have historically provided limited access to information about the occurrence of disease progression. As a result, progression-free survival (PFS), a standard effectiveness outcome measure in oncology, has been calculated using proxies such as time-to-discontinuation (TTD) or time-to-next-treatment (TTNT). However, electronic medical record (EMR) data sources that allow detailed curation of unstructured content make it possible to calculate PFS based on directly observed progression. The aim of this research was to compare PFS as estimated from proxy TTD and TTNT values with PFS determined directly from curated progression data. This report cites findings from the metastatic breast cancer (mBC) setting.