2623 - Patterns of Care of Brain Metastasis for Non-Small Cell Lung Cancer (NSCLC) in the Era of Immunotherapy

S. S. Varghese¹, S. Zahid², P. Markley³, S. Yiqing⁴, Y. Cao¹, Y. Hou¹, T. Stepp⁵, and F. Wang¹; ¹Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, KS, ²Kansas City University, Kansas city, KS, ³University of Kansas, School of medicine, Kansas city, KS, ⁴The university of Kansas health system, Topeka, KS, ⁵Department of Neurosurgery, The University of Kansas Medical center, Kansas City, KS

Purpose/Objective(s): Stereotactic radiosurgery (SRS) is becoming mainstream of the treatment for brain metastases in NSCLC patients to reduce potential neurotoxicity given the immunotherapy showing the prominent outcome of the longer survival. This retrospective study was designed to evaluate the pattern of the care and factors associated with overall survival in patients with multiple brain metastases from NSCLC. Materials/

Methods: 225 NSCLC patients with 705 total brain metastatic lesions who were treated with SRS from June 2009 – August 2021 were included in this IRB approved retrospective study. We collected data on the number of brain metastases, total number of SRS, total volume of lesions treated, PD-L1, EGFR, ALK and ROS status, incidence of radiation necrosis (RN) and overall survival (OS) of these patients. The OS was calculated from date of first SRS to the date of death or date of last follow up. Statistical analysis using Cox proportional hazard model was used to identify factors influencing OS and significant factors were entered into multivariate analysis.
Results: There were 225 patients with 705 treated brain metastatic lesions. The median age was 63 years (range: 35-95 years). 73 (32.4%) patients were positive for PD-L1expression (>1%), 26 for EGFR, 6 for ALK and 3 for ROS. The median follow-up was 16.7 months (range 0.06 – 120.5 months) and the median survival was 13.8 months (95% CI: 10.1 -17.1 months) for the entire group. The median number of lesions treated per patient was 2 (range: 1-27). The median total number of SRS per patient was 1 (range 1-6). The median total volume of lesions treated was 3.4 cc (range: 0.02 – 72.94 cc). 35 (15.5%) patients had salvage whole brain radiotherapy. On univariate analysis, PD-L1 status, presence of RN, total number of SRS, total volume of treated lesions significantly affected survival. On multivariate analysis, PD-L1 positive status and the presence of RN significantly impacted the OS. The median survival in months for PD-L1 negative patients was 21.412 ± 2.178 vs 41.672 ± 5.819 for PD-L 1 positive patients with P = 0.0372 and HR 0.686 (95% CI: 0.481 -0.978). The median number of SRS and mean volume of treated lesions were 1 and 6.887cc in PD-L1 positive patients, respectively. The incidence of RN was higher (28%) in PD-L 1 positive compared to 18% in the negative group. The median OS of patients with RN was 31.7 months compared to 11.8 months in patients without RN (P=0.0006). RN was a strong predictive factor for survival in patients with PD-L1 negative status than with positive status (P =0.0024)
Conclusion: PD-L 1 positive status and presence of RN are significant predictors of improved OS in NSCLC brain metastases treated with SRS. The impact of RN on survival was more pronounced in the PD-L1 negative group compared to the positive group.