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 com- pared 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 SAT 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.

Automated summary

In a multicentric retrospective study from AIRO, the combination of stereotactic radiotherapy (SRT) and immunotherapy (IT) showed better intracranial local progression-free survival in non-small cell lung cancer (NSCLC) patients with brain metastases. Additionally, treating NSCLC patients with IT after extracranial progression at the time of brain metastases diagnosis was associated with improved overall survival.