Neurological Benefits of a Radiosurgery-alone Approach to Small Cell Lung Cancer Brain Metastases

Introduction: Management of brain metastases has evolved to generally favor stereotactic radiosurgery over whole brain radiation given its favorable neurocognitive toxicity profile. This remains controversial in patients with small cell lung cancer. In a cohort of patients with SCLC treated with SRS, we review the rate of symptomatic intracranial progression and evaluate association between SRS failure and prior whole brain irradiation.

Methods: Records were obtained for all patients treated with Gamma Knife radiosurgery for brain metastasis from SCLC from April 2014 to April 2022. Outcomes of neurologic symptom-free survival (NFS: time from GKRS to steroid treatment due to intracranial disease progression) and intracranial progression-free survival (iPFS) were recorded. Inferential statistics were applied to generate Kaplan-Meier curves of NFS and iPFS. Significance values and statistical parameters are reported. Analysis was performed using IBM SPSS using a P value < 0.05 for statistical significance.

Results: 46 patients were identified. Median brain metastases, tumor size, and SRS dose were 2, 0.15 cc, and 20 Gy/1fx, respectively. 6 and 12 month iPFS were 42% and 23%; 6 month and 12 month NFS were 96% and 90%. 4 patients presented with neurological symptoms following SRS secondary to progression of disease, including headache, gait instability, and dysarthria. 9 patients were treated with steroids for prophylaxis or to mitigate treatment effects. Prior whole brain irradiation was non-significant for association with either iPFS or NFS. One neurologic death was confirmed at final follow-up.

Conclusion : SRS can be used to manage brain metastases from SCLC. CNS relapse in this population is unsurprising, but symptomatic progression can be avoided with MRI surveillance and focal salvage therapy. Given previous studies showing no compromise of survival with radiosurgical management, our study supports the utility of SRS in optimizing neurocognitive quality of life in this patient population.