Is it possible to delay stereotactic radiotherapy of brain metastasis of lung cancer?

Abstract Purpose Because modern medical treatments of lung cancer had a potential efficacy on brain metastases, the optimal timing of stereotactic radiosurgery (SRT) could be discussed. The aim of this retrospective study is to evaluate the outcomes according to the timing of SRT during the course of the disease. Materials and Methods all patients receiving SRT for BM of a lung cancer were included in the study, except those receiving whole brain radiotherapy (WBRT). We defined three groups of patients, according to the timing of SRT: L1 for those receiving SRT during the first line of medical treatment, L2 during the second line and L3 for others line. We analyzed local control of the treated metastases (LC), occurrence of new BM and overall survival (OS). For the two last variables, we calculated the probability of event from the date of SRT and from the first day of medical treatment (D1L1). Results 109 patients were included in the study and 102 evaluable for all parameters. LC did not differ if SRT was performed during L1, L2 or L3. Occurrence of new BM is delayed when SRT is performed in L1 and the initial point the time of SRT, but this difference disappeared when the probability of new BM is calculated from D1L1. No difference in OS was observed according to the timing of SRT. Conclusion this study underlines the important role of medical treatment to prevent new BM. In view of our results, SRT could be delayed if the medical treatment has a good probability of controlling BM progression.