Abstract Lung cancer(LC) is leading cause of brain metastasis(BM). Local treatment, surgery, stereotactic radiosurgery(SRS) and whole brain radiotherapy are mainstays of treatment. With Next generation sequencing(NGS), KRAS mutation(KRAS+)is estimated up-to 25% of LC having poor prognosis. This study investigates incidence and outcomes of KRAS+ LC with BM treated in our institution. Methods: A retrospective review of 473 patients with StageIV NSCLC and BM, treated with SRS between 2018-2023 was conducted and 161 patients were selected based on available NGS results (KRAS+ and KRAS-wild type). Demographic and treatment information were collected and statistical analyses, including univariate, multivariate(MVA) and propensity score matching(PSM) were performed. Results: Among 161 patients, 81 had KRAS+, 80 had KRAS-. At presentation, 65(40%) had single BM and surgery was performed in 83(52%) patients. Most patients received single fraction SRS (70%).Recurrence rates were comparable between KRAS+ and KRAS-25(31%)vs.29(36%)p=0.4. CNS recurrence rate remained consistent across groups regardless of SRS fractionation(p=0.84). At first progression, 4(21%) KRAS+ received salvage WBRT vs 7(27%)KRAS-(p=0.1). CNS PFS and OS didnot differ significantly(p=0.2, p=0.5). Pre-PSM, analysis identified ECOG, Age, biological effective dose(BED), BM size, salvage local treatment and extracranial disease progression as prognostic factors for OS(p=0.037). After PSM, BED48 was significantly associated with CNS PFS (p=0.01) Conclusion: This study presents unique findings indicating KRAS+ LC with BM has a similar recurrence rate with a trend suggesting lower use of salvage WBRT to KRAS-.Further studies to evaluate impact of KRAS inhibitors and SRS on BM outcomes are needed.
Karim et al. (Fri,) studied this question.