Survival among patients with untreated metastatic breast cancer: “What if I do nothing?”

Purpose We sought to assess survival outcomes of patients with de novo metastatic breast cancer (dnMBC) who did not receive treatment irrespective of the reason. Methods Adults with dnMBC were selected from the NCDB (2010–2016) and stratified based on receipt of treatment (treated = received at least one treatment and untreated = received no treatments). Overall survival (OS) was estimated using the Kaplan–Meier method, and groups were compared. Cox proportional hazards models were used to identify factors associated with OS. Results Of the 53,240 patients with dnMBC, 92.1% received at least one treatment (treated), and 7.9% had no documented treatments, irrespective of the reason (untreated). Untreated patients were more likely to be older (median 68 y vs 61 y, p