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Location: Marriott Marquis
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PQA 03 - PQA 03 Gynecological Cancer, Pediatric Cancer, and Professional Development Poster Q&A

3514 - Prognostic Factors in H3K7M-Mutant Diffuse Midline Gliomas

Monday, September 30, 2024
8:00 AM – 9:00 AM ET
Location: Hall C

Screen: 13

S. Induni1, H. Soderholm2, and K. B. Pointer3; 1Georgetown University, Washington, DC, 2Dartmouth, Lebanon, NH, 3University of Wisconsin-Madison, Madison, WI

Purpose/Objective(s): Diffuse midline glioma (DMG) is an aggressive brain tumor. DMGs represent 15-20% of all pediatric central nervous system tumors, with 200-300 new cases diagnosed per year in the United States. Roughly 70% of DMG samples contain a H3K27M mutation. There has been no significant progress in treatment for DMG made in the last 50 years with the standard of care mainly being radiation therapy. Despite treatment, H3K27M DMG is universally fatal. Due to the rare nature of H3K27M DMGs, further understanding of what drives prognosis and outcomes is needed. The purpose of this study was to determine demographic, clinical, and treatment variables that impact overall survival (OS) in H3K27M DMG. Materials/

Methods: Data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare Database from 2018-2020 was used to investigate prognostic factors that impact OS in patients with H3K27M DMG. 206 patients under the SEER category “1.1.3 Diffuse midline Glioma H327KM” were included in the study. Age, race, region in the United States, rural-urban location, household income, year of diagnosis, months from diagnosis to treatment, grade, laterality, extent of disease, tumor size, chromosome 19q and 1p loss of heterozygosity, chemotherapy, radiation, surgery, and surgery/radiation sequence were analyzed as factors that may impact OS. Univariate analysis was performed. Variables with a p-value < 0.05 were analyzed using the multivariate Cox proportional hazards model. Statistical software was used for statistical analysis. A p-value < 0.05 was considered statistically significant.

Results: The median age at diagnosis was 12 years old, 44.2% of the patients were male, and 55.8% of the patients were female. The median OS for patients with H327KM DMG was 14 months (95% CI = 11.574-16.426) with a 1-year survival rate of 54.1% and a 2-year survival rate of 26.8%. On multivariate analysis radiation treatment, sex, and age were statistically significant factors that influenced OS. Individuals who received radiation treatment survived significantly longer than individuals who did not receive radiation (p = 0.042); males survived significantly longer than females (p = 0.006); and younger individuals (£12) had a statistically significant better OS than older individuals (>12) (p = 0.008). There were no differences in OS based on other variables.

Conclusion: Radiation, sex, and age were identified as variables that were statistically significant for OS in individuals with H3K27M DMG. These data provide useful insight about factors that influence H3K27M DMG.
Abstract 3514 – Table 1: Multivariate Cox proportional hazards model
(p-value) Hazard ratio (HR) 95% CI for HR
Sex (female vs. male) - females have higher hazard 0.006 * 1.732 [1.169, 2.566]
Surgery (performed vs. not performed) 0.096 0.716 [0.484, 1.060]
Radiation (treatment vs. no treatment) 0.042 * 0.545 [0.303, 0.978]
Chemotherapy (treatment vs. no treatment) 0.212 0.767 [0.505, 1.164]
Age (1-12 years old vs. 12+ years old) 0.008 * 0.563 [0.368, 0.861]