RADT-11. HIGH INCIDENCE AND OUTCOME OF MULTICENTRIC HIGH GRADE GLIOMA (MCHGG) COMPARED TO UNICENTRIC HIGH GRADE GLIOMA (UCHGG), IN A MIDWEST REGIONAL CANCER CENTER SERVING A RURAL OUTREACH AREA, WHICH DRAWS FROM A 100 MILE RADIUS

Abstract A retrospective review was conducted on patients diagnosed with high grade glioma between January 2022 and January 2025. Patient demographics including age, gender, geographic area, number of discrete lesions, molecular alterations including methylation, IDH, ATRX, Ki-67, p53, family history, and treatment modalities were evaluated. Kaplan-Meier analysis was used to assess overall survival (OS), while the log-rank test compared survival differences between MCHGG and UCHGG. Univariable logistic regression evaluated the likelihood of factors associated with MCHGG, and Cox regression analysis assessed potential prognostic factors. Of 38 patients with high grade gliomas, 12 (31%) had MCHGG with a range of 2 to 9 lesions (median of 3). The median follow-up for all patients was 8 months (M) (range: 0.39–29) with 23 total deaths. The overall median survival (MS) for the cohort was 12M (95% CI: 7–22). Patients with MCHGG demonstrated a trend toward inferior OS compared to those with UCHGG, with MS of 8M (95% CI: 2–11) versus 14M (95% CI: 5–25), and 6-, 12-, and 24M OS rates of 58%, 0%, and 0% for MCHGG versus 64%, 54%, and 26% for UCHGG (p=0.06). Univariable logistic regression indicated that UCHGG patients were significantly more likely to undergo surgical resection (OR 6.667, p=0.01). Univariable Cox regression revealed that UCHGG, surgery, Temodar/radiation are the only factors associated with improved survival. Multivariable Cox regression revealed that MCHGG was associated with a higher risk of death at 12M (HR 2.663, p=0.04), after adjusting for surgical resection and Temodar/radiation. At this Center, MCHGG represents 31% of cases, higher than published studies (<10%). MCHGG patients have poorer OS compared to UCHGG patients, 8 vs 14 M respecitvely. Patients with MCHGG were less likely to receive surgical resection which could account for worse OS. Further investigation with larger studes is warranted.