Immunotherapy in association with stereotactic radiotherapy for non-small cell lung cancer brain metastases: results from a multicentric retrospective study on behalf of AIRO

Background: To define efficacy and toxicity of Immunotherapy (IT) with stereotactic radiotherapy (SRT) including radiosurgery (RS) or hypofractionated SRT (HFSRT) for brain metastases (BM) from non-small cell lung cancer (NSCLC) in a multicentric retrospective study from AIRO (Italian Association of Radiotherapy and Clinical Oncology). Methods: NSCLC patients with BM receiving SRT + IT and treated in 19 Italian centers were analyzed and compared with a control group of patients treated with exclusive SRT. Results: One hundred patients treated with SRT + IT and 50 patients treated with SRT-alone were included. Patients receiving SRT + IT had a longer intracranial Local Progression-Free Survival (iLPFS) (propensity score-adjusted P =. 007). Among patients who, at the diagnosis of BM, received IT and had also extracranial progression (n = 24), IT administration after SRT was shown to be related to a better overall survival (OS) (P =. 037). A multivariate analysis, non-adenocarcinoma histology, KPS = 70 and use of HFSRT were associated with a significantly worse survival (P =. 019, P =. 017 and P =. 007 respectively). Time interval between SRT and IT ≤7 days (n = 90) was shown to be related to a longer OS if compared to SRT-IT interval >7 days (n = 10) (propensity score-adjusted P =. 008). The combined treatment was well tolerated. No significant difference in terms of radionecrosis between SRT + IT patients and SRT-alone patients was observed. The time interval between SRT and IT had no impact on the toxicity rate. Conclusions: Combined SRT + IT was a safe approach, associated with a better iLPFS if compared to exclusive SRT.