Real world outcomes of patients with small cell lung cancer (SCLC) presenting with brain metastasis at diagnosis in a single institution health system.

e20136 Background: Extensive-stage small cell lung cancer (ES-SCLC) is an aggressive lung cancer subtype with high propensity for brain metastases (mets). Despite this, there is no consensus on the treatment of brain mets especially in the setting of frontline chemoimmunotherapy and advanced radiation techniques like Gamma Knife radiosurgery (GKRS). Methods: In this single-institution retrospective study, we queried the Yale Tumor registry for all patients diagnosed with ES-SCLC in 1/2016-4/2023. Patients with brain mets at the time of presentation were identified and underwent manual chart review for abstraction of clinical information specifically pertaining to brain mets and treatment modalities. Survival outcomes including median progression free survival (mPFS), median central nervous system-progression free survival (mcPFS) and median overall survival (mOS) measured in months were also captured. Results: 423 ES-SCLC patients were identified. Of those, 92 (22%) had brain mets at initial presentation and were reviewed. 44 (48%) of patients with brain mets were treated with frontline chemotherapy (platinum doublet) while 42 (46%) were treated with chemoimmunotherapy (platinum doublet with atezolizumab or durvalumab). Patients treated with upfront chemotherapy had mPFS 6.4 (95% CI -1.2, 14.1), mcPFS 7.7 (95% CI -1.2, 17.1), and mOS 9.3 (95% CI -13.7, 36.4), compared to patients treated with chemoimmunotherapy, who had mPFS 4.9 (p=0.23; 95% CI -3.5, 15.4), mcPFS 6.7 (p=0.99; 95% CI 3.3, 20.8), and mOS 7.7 (p=0.89; 95% CI -11.4, 33.9). 63 (68%) of patients underwent upfront brain radiation. 44 (48%) had whole brain radiation (WBRT) while 19 (30%) underwent GKRS. Of the patients undergoing GKRS, 8 (42%) were symptomatic. 7 patients (37%) presented with 1 brain met, and 12 (63%) patients presented with 2-5 brain mets. For patients treated with GKRS, mPFS 6.8 (95% CI 2.3, 10.4), mcPFS 7.2 (95% CI 2.9, 12.6), and mOS 11.1 (95% CI -13.0, 40.9). For patients undergoing WBRT, mPFS 6.5 (p = 1.0; 95% CI -4.5, 20.2), mcPFS 6.5 (p = 0.96; 95% CI -3.9, 21.6), and mOS 8.6 (p = 0.21; 95% CI -17.7, 39.9). Conclusions: GKRS is a viable option for SCLC patients presenting with brain metastases, especially in those with a low number of mets. Further studies are required to determine the optimal ES-SCLC candidates for upfront GKRS. [Table: see text]