The time interval between palliative thoracic radiotherapy and bevacizumab treatment strongly influences the frequency of adverse events (AEs) when both are concurrently applied to patients with advanced lung cancer. Herein, we aimed to elucidate the optimal time interval between the treatments in these patients.

The medical records of patients with stage IV nonsquamous non-small-cell lung cancer (NSCLC) without epidermal growth factor receptor and anaplastic lymphoma kinase alteration who underwent palliative thoracic radiotherapy and bevacizumab treatment from January 2008 to January 2020 were collected and analyzed. Patients were divided into 2 groups based on the time interval between treatments: <3 weeks (⩽3W group) and >3 weeks (>3W group). The progression-free survival (PFS) and overall survival (OS) for the time intervals were evaluated using the Kaplan-Meier method and Cox proportional hazard models. Adverse events were assessed by the fifth version of the Common Terminology Criteria for Adverse Events.

In total, 72 patients with stage IV NSCLC (⩽3W group, 37 patients; >3W group, 35 patients) who concurrently or sequentially received palliative thoracic radiotherapy and bevacizumab treatment were included in this study. In the >3W and ⩽3W groups, the median PFS (8 vs 6 months, respectively) and OS (15 vs 12 months, respectively) differed significantly. Multivariate analyses findings revealed significantly shorter OS in the latter group. In addition, the frequency of most AEs was marginally higher in the latter group ( > .05).

The time interval between palliative thoracic radiotherapy and bevacizumab treatment that offers optimal safety is >3 weeks.