EPID-24. TIMING OF STANDARD-OF-CARE CHEMO-RADIATION THERAPY FOLLOWING SURGICAL RESECTION OR STEREOTACTIC BIOPSY

Abstract OBJECT The literature examining the optimal timing for initiating post-surgical therapy after glioblastoma surgery is brimming with inconsistencies, reports of both deleterious effects and benefits in delay at various time intervals. Moreover, there currently limited data pertinent to post-Stupp regimen era. Here, we use National Cancer Database (NCDB) explore this matter, a focus on patients who underwent standard-of-care (SOC) Stupp regimen. METHODS study cohort included newly from NCDB, exclusion age < 40 [as proxy isocitrate dehydrogenase (IDH) mutated astrocytoma] stratified Methyl-guanine-methyl transferase (MGMT) promotor methylation. Timing SOC was grouped by 0-2, 2-4, 4-6, 6-8, > 8 weeks surgery. Biopsy craniotomy were analyzed separately. Kaplan-Meier method Cox proportional hazards regression applied survival analysis. RESULTS We identified 6511 available MGMT methylation status. initiated 228 (3.5%), 2478 (38.1%), 2954 (45.4%), 646 (9.9%), 205 (3.2%) >8 For patients, initiation 0-2 associated an increased risk death relative 4-6 (HR: 1.19, p = 0.036). These results remain robust controlling extent resection, tumor size, location 0.044). Such association not observed stereotactic biopsy 1.27, 0.148). Patients received 6-8 post-craniotomy 0.96, 0.420) or 0.93, 0.628) did appear worsen outcomes. CONCLUSION Optimal differ needle patients. Initiating within 2 could lead worse outcomes GBM