Line of therapy (LOT) definition impacts second-line (2L) survival duration in a metastatic pancreatic cancer (mPCa) electronic health record database.

300Background: Establishing an accurate LOT definition in real-world data (RWD) oncology studies is critical for measuring the effects of treatments on outcomes, which informs decisions made by clinicians, regulators, and payers. However, measuring LOT in RWD analyses is challenging and varies across disease states. LOT is generally defined by treatment (tx) start and stop dates. When available, the date of disease progression (PD) can be used to enhance the LOT definition. We explored the analytical impact of varying LOT definitions on 2L survival outcomes. Methods: A retrospective analysis of patients (pts) with mPC treated in US community practices was conducted using the Flatiron Health EHR–derived database. Two algorithms were applied to define LOT: tx change or ≥ 60-day gap in tx (LOTtx) and tx change after first PD (LOTpd). The impact on 1L and 2L sample sizes as well as 2L overall survival (OS) and progression-free survival (PFS) were assessed. Results: 251 pts with an mPC diagnosis between 01 Mar...